Merge branch 'rickard/ohmq/OTP-13047'

* rickard/ohmq/OTP-13047:
  Fragmented young heap generation and off_heap_message_queue option
  Refactor GC
  Introduce literal tag

Conflicts:
	erts/doc/src/erlang.xml
	erts/emulator/beam/erl_gc.c

43 files changed, 2913 insertions, 2160 deletions

diff --git a/erts/configure.in b/erts/configure.in
index a4700fc308..2419925c33 100644
--- a/erts/configure.in
+++ b/erts/configure.in
@@ -3711,7 +3711,7 @@ dnl crypto
 #
 #--------------------------------------------------------------------
 
-DED_SYS_INCLUDE="-I${ERL_TOP}/erts/emulator/beam -I${ERL_TOP}/erts/include -I${ERL_TOP}/erts/include/$host -I${ERL_TOP}/erts/include/internal -I${ERL_TOP}/erts/include/internal/$host -I${ERL_TOP}/erts/emulator/sys/$ERLANG_OSTYPE"
+DED_SYS_INCLUDE="-I${ERL_TOP}/erts/emulator/beam -I${ERL_TOP}/erts/include -I${ERL_TOP}/erts/include/$host -I${ERL_TOP}/erts/include/internal -I${ERL_TOP}/erts/include/internal/$host -I${ERL_TOP}/erts/emulator/sys/$ERLANG_OSTYPE -I${ERL_TOP}/erts/emulator/sys/common"
 
 if test "X$ETHR_DEFS" = "X"; then
     DED_THR_DEFS="-D_THREAD_SAFE -D_REENTRANT"
diff --git a/erts/doc/src/erl.xml b/erts/doc/src/erl.xml
index ec4a0dee05..c4eb0e16ec 100644
--- a/erts/doc/src/erl.xml
+++ b/erts/doc/src/erl.xml
@@ -1334,6 +1334,21 @@
           <seealso marker="kernel:error_logger#warning_map/0">error_logger(3)</seealso>
           for further information.</p>
       </item>
+      <tag><c><![CDATA[+xFlag Value]]></c></tag>
+      <item>
+        <p>Default process flag settings.</p>
+        <taglist>
+          <tag><marker id="+xohmq"><c>+xohmq true|false</c></marker></tag>
+          <item><p>
+	    Sets the default value for the process flag
+	    <c>off_heap_message_queue</c>. If <c>+xohmq</c> is not
+	    passed, <c>false</c> will be the default. For more information,
+	    see the documentation of
+            <seealso marker="erlang#process_flag_off_heap_message_queue"><c>process_flag(off_heap_message_queue,
+	    OHMQ)</c></seealso>.
+	  </p></item>
+	</taglist>
+      </item>
       <tag><c><![CDATA[+zFlag Value]]></c></tag>
       <item>
         <p>Miscellaneous flags.</p>
diff --git a/erts/doc/src/erlang.xml b/erts/doc/src/erlang.xml
index 93e42c1230..2e82bb62a9 100644
--- a/erts/doc/src/erlang.xml
+++ b/erts/doc/src/erlang.xml
@@ -4280,9 +4280,46 @@ os_prompt% </pre>
         <p>Returns the old value of the flag.</p>
       </desc>
     </func>
-
+    <marker id="process_flag_off_heap_message_queue"/>
     <func>
       <name name="process_flag" arity="2" clause_i="5"/>
+      <fsummary>Set process flag <c>off_heap_message_queue</c> for the calling process</fsummary>
+      <desc>
+	<p>This flag determines how messages in the message queue
+	are stored. When the flag is:</p>
+        <taglist>
+          <tag><c>true</c></tag>
+	  <item><p>
+	    <em>All</em> messages in the message queue will be stored
+	    outside of the process heap. This implies that <em>no</em>
+	    messages in the message queue will be part of a garbage
+	    collection of the process.
+	  </p></item>
+          <tag><c>false</c></tag>
+	  <item><p>
+	    Messages may be placed either on the heap or outside
+	    of the heap.
+	  </p></item>
+        </taglist>
+	<p>
+	  If the process potentially may get a hugh amount of messages,
+	  you are recommended to set the flag to <c>true</c>. This since
+	  a garbage collection with lots of messages placed on the heap
+	  may become extremly expensive. Performance of the actual
+	  message passing is however generally better when setting the
+	  flag to <c>false</c>.
+	</p>
+	<p>
+	  When changing this flag from <c>false</c> to <c>true</c>,
+	  all messages in the message queue are moved off heap. This
+	  work has been initiated but not completed when this function
+	  call returns.
+	</p>
+        <p>Returns the old value of the flag.</p>
+      </desc>
+    </func>
+    <func>
+      <name name="process_flag" arity="2" clause_i="6"/>
       <fsummary>Sets process flag <c>priority</c> for the calling process.</fsummary>
       <type name="priority_level"/>
       <desc>
@@ -4356,7 +4393,7 @@ os_prompt% </pre>
     </func>
 
     <func>
-      <name name="process_flag" arity="2" clause_i="6"/>
+      <name name="process_flag" arity="2" clause_i="7"/>
       <fsummary>Sets process flag <c>save_calls</c> for the calling process.</fsummary>
       <desc>
         <p><c><anno>N</anno></c> must be an integer in the interval 0..10000.
@@ -4387,7 +4424,7 @@ os_prompt% </pre>
     </func>
 
     <func>
-      <name name="process_flag" arity="2" clause_i="7"/>
+      <name name="process_flag" arity="2" clause_i="8"/>
       <fsummary>Sets process flag <c>sensitive</c> for the calling process.</fsummary>
       <desc>
         <p>Sets or clears flag <c>sensitive</c> for the current process.
@@ -4661,6 +4698,14 @@ os_prompt% </pre>
               monitor by name, the list item is
               <c>{process, {<anno>RegName</anno>, <anno>Node</anno>}}</c>.</p>
           </item>
+          <tag><c>{off_heap_message_queue, <anno>OHMQ</anno>}</c></tag>
+          <item>
+            <p>Returns the current state of the <c>off_heap_message_queue</c>
+	    process flag. <c><anno>OHMQ</anno></c> is either <c>true</c>, or
+	    <c>false</c>. For more information, see the documentation of
+            <seealso marker="#process_flag_off_heap_message_queue"><c>process_flag(off_heap_message_queue,
+	    OHMQ)</c></seealso>.</p>
+          </item>
           <tag><c>{priority, <anno>Level</anno>}</c></tag>
           <item>
             <p><c><anno>Level</anno></c> is the current priority level for
@@ -5429,6 +5474,7 @@ true</pre>
       <name name="spawn_opt" arity="2"/>
       <fsummary>Creates a new process with a fun as entry point.</fsummary>
       <type name="priority_level"/>
+      <type name="spawn_opt_option" />
       <desc>
         <p>Returns the process identifier (pid) of a new process
           started by the application of <c><anno>Fun</anno></c>
@@ -5444,6 +5490,7 @@ true</pre>
       <name name="spawn_opt" arity="3"/>
       <fsummary>Creates a new process with a fun as entry point on a given node.</fsummary>
       <type name="priority_level"/>
+      <type name="spawn_opt_option" />
       <desc>
         <p>Returns the process identifier (pid) of a new process started
           by the application of <c><anno>Fun</anno></c> to the
@@ -5458,6 +5505,7 @@ true</pre>
       <name name="spawn_opt" arity="4"/>
       <fsummary>Creates a new process with a function as entry point.</fsummary>
       <type name="priority_level"/>
+      <type name="spawn_opt_option" />
       <desc>
         <p>Works as
           <seealso marker="#spawn/3">spawn/3</seealso>, except that an
@@ -5559,6 +5607,18 @@ true</pre>
               fine-tuning an application and to measure the execution
               time with various <c><anno>VSize</anno></c> values.</p>
           </item>
+          <tag><c>{off_heap_message_queue, <anno>OHMQ</anno>}</c></tag>
+          <item>
+            <p>Sets the state of the <c>off_heap_message_queue</c> process
+	    flag. <c><anno>OHMQ</anno></c> should be either <c>true</c>, or
+	    <c>false</c>. The default <c>off_heap_message_queue</c> process
+	    flag is determined by the
+	    <seealso marker="erl#+xohmq"><c>+xohmq</c></seealso> <c>erl</c>
+	    command line argument. For more information, see the
+	    documentation of
+            <seealso marker="#process_flag_off_heap_message_queue"><c>process_flag(off_heap_message_queue,
+	    <anno>OHMQ</anno>)</c></seealso>.</p>
+          </item>
         </taglist>
       </desc>
     </func>
@@ -5567,6 +5627,7 @@ true</pre>
       <name name="spawn_opt" arity="5"/>
       <fsummary>Creates a new process with a function as entry point on a given node.</fsummary>
       <type name="priority_level"/>
+      <type name="spawn_opt_option" />
       <desc>
         <p>Returns the process identifier (pid) of a new process started
           by the application
@@ -6639,6 +6700,7 @@ ok
       <name name="system_info" arity="1" clause_i="65"/>
       <name name="system_info" arity="1" clause_i="66"/>
       <name name="system_info" arity="1" clause_i="67"/>
+      <name name="system_info" arity="1" clause_i="68"/>
       <fsummary>Information about the system.</fsummary>
       <desc>
         <p>Returns various information about the current system
@@ -7044,7 +7106,17 @@ ok
               used by the runtime system. It is on the form
 	      "&lt;major ver&gt;.&lt;minor ver&gt;".</p>
           </item>
-          <tag><c>otp_release</c></tag>
+          <tag><marker id="system_info_off_heap_message_queue"><c>off_heap_message_queue</c></marker></tag>
+          <item>
+            <p>Returns the default value of the <c>off_heap_message_queue</c>
+	    process flag which is either <c>true</c> or <c>false</c>. This
+	    default is set by the <c>erl</c> command line argument
+	    <seealso marker="erl#+xohmq"><c>+xohmq</c></seealso>. For more information on the
+	    <c>off_heap_message_queue</c> process flag, see documentation of
+            <seealso marker="#process_flag_off_heap_message_queue"><c>process_flag(off_heap_message_queue,
+	    OHMQ)</c></seealso>.</p>
+          </item>
+          <tag><marker id="system_info_otp_release"><c>otp_release</c></marker></tag>
           <item>
           <marker id="system_info_otp_release"></marker>
             <p>Returns a string containing the OTP release number of the
diff --git a/erts/emulator/beam/atom.names b/erts/emulator/beam/atom.names
index 967cf013f0..ea04495574 100644
--- a/erts/emulator/beam/atom.names
+++ b/erts/emulator/beam/atom.names
@@ -423,6 +423,7 @@ atom notify
 atom notsup
 atom nouse_stdio
 atom objects
+atom off_heap_message_queue
 atom offset
 atom ok
 atom old_heap_block_size
diff --git a/erts/emulator/beam/beam_bif_load.c b/erts/emulator/beam/beam_bif_load.c
index 2c275c4649..22b4e26c77 100644
--- a/erts/emulator/beam/beam_bif_load.c
+++ b/erts/emulator/beam/beam_bif_load.c
@@ -723,29 +723,50 @@ set_default_trace_pattern(Eterm module)
     }
 }
 
+static ERTS_INLINE int
+check_mod_funs(Process *p, ErlOffHeap *off_heap, char *area, size_t area_size)
+{
+    struct erl_off_heap_header* oh;
+    for (oh = off_heap->first; oh; oh = oh->next) {
+	if (thing_subtag(oh->thing_word) == FUN_SUBTAG) {
+	    ErlFunThing* funp = (ErlFunThing*) oh;
+	    if (ErtsInArea(funp->fe->address, area, area_size))
+		return !0;
+	}
+    }
+    return 0;
+}
+
+
 static Eterm
 check_process_code(Process* rp, Module* modp, int allow_gc, int *redsp)
 {
     BeamInstr* start;
     char* literals;
     Uint lit_bsize;
-    BeamInstr* end;
+    char* mod_start;
+    Uint mod_size;
     Eterm* sp;
-    struct erl_off_heap_header* oh;
     int done_gc = 0;
+    int need_gc = 0;
+    ErtsMessage *msgp;
+    ErlHeapFragment *hfrag;
 
-#define INSIDE(a) (start <= (a) && (a) < end)
+#define ERTS_ORDINARY_GC__ (1 << 0)
+#define ERTS_LITERAL_GC__  (1 << 1)
 
     /*
      * Pick up limits for the module.
      */
     start = (BeamInstr*) modp->old.code_hdr;
-    end = (BeamInstr *)((char *)start + modp->old.code_length);
+    mod_start = (char *) start;
+    mod_size = modp->old.code_length;
 
     /*
      * Check if current instruction or continuation pointer points into module.
      */
-    if (INSIDE(rp->i) || INSIDE(rp->cp)) {
+    if (ErtsInArea(rp->i, mod_start, mod_size)
+	|| ErtsInArea(rp->cp, mod_start, mod_size)) {
 	return am_true;
     }
 
@@ -753,7 +774,7 @@ check_process_code(Process* rp, Module* modp, int allow_gc, int *redsp)
      * Check all continuation pointers stored on the stack.
      */
     for (sp = rp->stop; sp < STACK_START(rp); sp++) {
-	if (is_CP(*sp) && INSIDE(cp_val(*sp))) {
+	if (is_CP(*sp) && ErtsInArea(cp_val(*sp), mod_start, mod_size)) {
 	    return am_true;
 	}
     }
@@ -767,15 +788,15 @@ check_process_code(Process* rp, Module* modp, int allow_gc, int *redsp)
 	struct StackTrace *s;
 	ASSERT(is_list(rp->ftrace));
 	s = (struct StackTrace *) big_val(CDR(list_val(rp->ftrace)));
-	if ((s->pc && INSIDE(s->pc)) ||
-	    (s->current && INSIDE(s->current))) {
+	if ((s->pc && ErtsInArea(s->pc, mod_start, mod_size)) ||
+	    (s->current && ErtsInArea(s->current, mod_start, mod_size))) {
 	    rp->freason = EXC_NULL;
 	    rp->fvalue = NIL;
 	    rp->ftrace = NIL;
 	} else {
 	    int i;
 	    for (i = 0;  i < s->depth;  i++) {
-		if (INSIDE(s->trace[i])) {
+		if (ErtsInArea(s->trace[i], mod_start, mod_size)) {
 		    rp->freason = EXC_NULL;
 		    rp->fvalue = NIL;
 		    rp->ftrace = NIL;
@@ -796,108 +817,141 @@ check_process_code(Process* rp, Module* modp, int allow_gc, int *redsp)
     }
 
     /*
-     * See if there are funs that refer to the old version of the module.
+     * Message queue can contains funs, but (at least currently) no
+     * constants. If we got references to this module from the message
+     * queue, a GC cannot remove these...
      */
 
- rescan:
-    for (oh = MSO(rp).first; oh; oh = oh->next) {
-	if (thing_subtag(oh->thing_word) == FUN_SUBTAG) {
-	    ErlFunThing* funp = (ErlFunThing*) oh;
+    erts_smp_proc_lock(rp, ERTS_PROC_LOCK_MSGQ);
+    ERTS_SMP_MSGQ_MV_INQ2PRIVQ(rp);
+    erts_smp_proc_unlock(rp, ERTS_PROC_LOCK_MSGQ);
 
-	    if (INSIDE((BeamInstr *) funp->fe->address)) {
-		if (done_gc) {
-		    return am_true;
-		} else {
-		    if (!allow_gc)
-			return am_aborted;
-		    /*
-		    * Try to get rid of this fun by garbage collecting.
-		    * Clear both fvalue and ftrace to make sure they
-		    * don't hold any funs.
-		    */
-		    rp->freason = EXC_NULL;
-		    rp->fvalue = NIL;
-		    rp->ftrace = NIL;
-		    done_gc = 1;
-		    FLAGS(rp) |= F_NEED_FULLSWEEP;
-		    *redsp += erts_garbage_collect(rp, 0, rp->arg_reg, rp->arity);
-		    goto rescan;
-		}
-	    }
+    for (msgp = rp->msg.first; msgp; msgp = msgp->next) {
+	if (msgp->data.attached == ERTS_MSG_COMBINED_HFRAG)
+	    hfrag = &msgp->hfrag;
+	else if (is_value(ERL_MESSAGE_TERM(msgp)) && msgp->data.heap_frag)
+	    hfrag = msgp->data.heap_frag;
+	else
+	    continue;
+	for (; hfrag; hfrag = hfrag->next) {
+	    if (check_mod_funs(rp, &hfrag->off_heap, mod_start, mod_size))
+		return am_true;
+	    /* Should not contain any constants... */
+	    ASSERT(!any_heap_ref_ptrs(&hfrag->mem[0],
+				      &hfrag->mem[hfrag->used_size],
+				      mod_start,
+				      mod_size));
 	}
     }
 
-    /*
-     * See if there are constants inside the module referenced by the process.
-     */
-    done_gc = 0;
     literals = (char*) modp->old.code_hdr->literals_start;
     lit_bsize = (char*) modp->old.code_hdr->literals_end - literals;
-    for (;;) {
-	ErlMessage* mp;
 
+    while (1) {
+
+	/* Check heap, stack etc... */
+	if (check_mod_funs(rp, &rp->off_heap, mod_start, mod_size))
+	    goto try_gc;
 	if (any_heap_ref_ptrs(&rp->fvalue, &rp->fvalue+1, literals, lit_bsize)) {
 	    rp->freason = EXC_NULL;
 	    rp->fvalue = NIL;
 	    rp->ftrace = NIL;
 	}
-	if (any_heap_ref_ptrs(rp->stop, rp->hend, literals, lit_bsize)) {
-	    goto need_gc;
-	}
-	if (any_heap_refs(rp->heap, rp->htop, literals, lit_bsize)) {
-	    goto need_gc;
-	}
+	if (any_heap_ref_ptrs(rp->stop, rp->hend, literals, lit_bsize))
+	    goto try_literal_gc;
+	if (any_heap_refs(rp->heap, rp->htop, literals, lit_bsize))
+	    goto try_literal_gc;
+	if (any_heap_refs(rp->old_heap, rp->old_htop, literals, lit_bsize))
+	    goto try_literal_gc;
+
+	/* Check dictionary */
+	if (rp->dictionary) {
+	    Eterm* start = rp->dictionary->data;
+	    Eterm* end = start + rp->dictionary->used;
 
-	if (any_heap_refs(rp->old_heap, rp->old_htop, literals, lit_bsize)) {
-	    goto need_gc;
+	    if (any_heap_ref_ptrs(start, end, literals, lit_bsize))
+		goto try_literal_gc;
 	}
 
-	if (rp->dictionary != NULL) {
-	    Eterm* start = rp->dictionary->data;
-	    Eterm* end = start + rp->dictionary->used;
+	/* Check heap fragments */
+	for (hfrag = rp->mbuf; hfrag; hfrag = hfrag->next) {
+	    Eterm *hp, *hp_end;
+	    /* Off heap lists should already have been moved into process */
+	    ASSERT(!check_mod_funs(rp, &hfrag->off_heap, mod_start, mod_size));
 
-	    if (any_heap_ref_ptrs(start, end, literals, lit_bsize)) {
-		goto need_gc;
-	    }
+	    hp = &hfrag->mem[0];
+	    hp_end = &hfrag->mem[hfrag->used_size];
+	    if (any_heap_ref_ptrs(hp, hp_end, mod_start, lit_bsize))
+		goto try_literal_gc;
 	}
 
-	for (mp = rp->msg.first; mp != NULL; mp = mp->next) {
-	    if (any_heap_ref_ptrs(mp->m, mp->m+2, literals, lit_bsize)) {
-		goto need_gc;
+#ifdef DEBUG
+	/*
+	 * Message buffer fragments should not have any references
+	 * to constants, and off heap lists should already have
+	 * been moved into process off heap structure.
+	 */
+	for (msgp = rp->msg_frag; msgp; msgp = msgp->next) {
+	    if (msgp->data.attached == ERTS_MSG_COMBINED_HFRAG)
+		hfrag = &msgp->hfrag;
+	    else
+		hfrag = msgp->data.heap_frag;
+	    for (; hfrag; hfrag = hfrag->next) {
+		Eterm *hp, *hp_end;
+		ASSERT(!check_mod_funs(rp, &hfrag->off_heap, mod_start, mod_size));
+
+		hp = &hfrag->mem[0];
+		hp_end = &hfrag->mem[hfrag->used_size];
+		ASSERT(!any_heap_ref_ptrs(hp, hp_end, mod_start, lit_bsize));
 	    }
 	}
-	break;
 
-    need_gc:
-	if (done_gc) {
+#endif
+
+	return am_false;
+
+    try_literal_gc:
+	need_gc |= ERTS_LITERAL_GC__;
+
+    try_gc:
+	need_gc |= ERTS_ORDINARY_GC__;
+
+	if ((done_gc & need_gc) == need_gc)
 	    return am_true;
-	} else {
-	    struct erl_off_heap_header* oh;
 
-	    if (!allow_gc)
-		return am_aborted;
+	if (!allow_gc)
+	    return am_aborted;
 
-	    /*
-	     * Try to get rid of constants by by garbage collecting.
-	     * Clear both fvalue and ftrace.
-	     */
-	    rp->freason = EXC_NULL;
-	    rp->fvalue = NIL;
-	    rp->ftrace = NIL;
-	    done_gc = 1;
+	need_gc &= ~done_gc;
+
+	/*
+	 * Try to get rid of constants by by garbage collecting.
+	 * Clear both fvalue and ftrace.
+	 */
+
+	rp->freason = EXC_NULL;
+	rp->fvalue = NIL;
+	rp->ftrace = NIL;
+
+	if (need_gc & ERTS_ORDINARY_GC__) {
 	    FLAGS(rp) |= F_NEED_FULLSWEEP;
 	    *redsp += erts_garbage_collect(rp, 0, rp->arg_reg, rp->arity);
+	    done_gc |= ERTS_ORDINARY_GC__;
+	}
+	if (need_gc & ERTS_LITERAL_GC__) {
+	    struct erl_off_heap_header* oh;
 	    oh = modp->old.code_hdr->literals_off_heap;
 	    *redsp += lit_bsize / 64; /* Need, better value... */
 	    erts_garbage_collect_literals(rp, (Eterm*)literals, lit_bsize, oh);
+	    done_gc |= ERTS_LITERAL_GC__;
 	}
+	need_gc = 0;
     }
-    return am_false;
-#undef INSIDE
-}
 
-#define in_area(ptr,start,nbytes) \
-    ((UWord)((char*)(ptr) - (char*)(start)) < (nbytes))
+#undef ERTS_ORDINARY_GC__
+#undef ERTS_LITERAL_GC__
+
+}
 
 static int
 any_heap_ref_ptrs(Eterm* start, Eterm* end, char* mod_start, Uint mod_size)
@@ -910,7 +964,7 @@ any_heap_ref_ptrs(Eterm* start, Eterm* end, char* mod_start, Uint mod_size)
 	switch (primary_tag(val)) {
 	case TAG_PRIMARY_BOXED:
 	case TAG_PRIMARY_LIST:
-	    if (in_area(val, mod_start, mod_size)) {
+	    if (ErtsInArea(val, mod_start, mod_size)) {
 		return 1;
 	    }
 	    break;
@@ -930,7 +984,7 @@ any_heap_refs(Eterm* start, Eterm* end, char* mod_start, Uint mod_size)
 	switch (primary_tag(val)) {
 	case TAG_PRIMARY_BOXED:
 	case TAG_PRIMARY_LIST:
-	    if (in_area(val, mod_start, mod_size)) {
+	    if (ErtsInArea(val, mod_start, mod_size)) {
 		return 1;
 	    }
 	    break;
@@ -940,7 +994,7 @@ any_heap_refs(Eterm* start, Eterm* end, char* mod_start, Uint mod_size)
                 if (header_is_bin_matchstate(val)) {
                     ErlBinMatchState *ms = (ErlBinMatchState*) p;
                     ErlBinMatchBuffer *mb = &(ms->mb);
-                    if (in_area(mb->orig, mod_start, mod_size)) {
+                    if (ErtsInArea(mb->orig, mod_start, mod_size)) {
                         return 1;
                     }
                 }
@@ -953,8 +1007,6 @@ any_heap_refs(Eterm* start, Eterm* end, char* mod_start, Uint mod_size)
     return 0;
 }
 
-#undef in_area
-
 BIF_RETTYPE purge_module_1(BIF_ALIST_1)
 {
     ErtsCodeIndex code_ix;
diff --git a/erts/emulator/beam/beam_emu.c b/erts/emulator/beam/beam_emu.c
index f15b98eb58..cd2aee4bbf 100644
--- a/erts/emulator/beam/beam_emu.c
+++ b/erts/emulator/beam/beam_emu.c
@@ -1654,10 +1654,6 @@ void process_main(void)
      ERTS_VERIFY_UNUSED_TEMP_ALLOC(c_p);
      ERTS_SMP_REQ_PROC_MAIN_LOCK(c_p);
      PROCESS_MAIN_CHK_LOCKS(c_p);
-     if (c_p->mbuf || MSO(c_p).overhead >= BIN_VHEAP_SZ(c_p)) {
-	 result = erts_gc_after_bif_call(c_p, result, reg, 2);
-	 E = c_p->stop;
-     }
      HTOP = HEAP_TOP(c_p);
      FCALLS = c_p->fcalls;
      if (is_value(result)) {
@@ -1745,8 +1741,7 @@ void process_main(void)
 		 SWAPIN;
 	     }
 	     /* only x(2) is included in the rootset here */
-	     if (E - HTOP < 3 || c_p->mbuf) {	/* Force GC in case add_stacktrace()
-						 * created heap fragments */
+	     if (E - HTOP < 3) {
 		 SWAPOUT;
 		 PROCESS_MAIN_CHK_LOCKS(c_p);
 		 FCALLS -= erts_garbage_collect(c_p, 3, reg+2, 1);
@@ -1833,10 +1828,17 @@ void process_main(void)
  OpCase(i_loop_rec_f):
  {
      BeamInstr *next;
-     ErlMessage* msgp;
+     ErtsMessage* msgp;
 
- loop_rec__:
+     /*
+      * We need to disable GC while matching messages
+      * in the queue. This since messages with data outside
+      * the heap will be corrupted by a GC.
+      */
+     ASSERT(!(c_p->flags & F_DISABLE_GC));
+     c_p->flags |= F_DISABLE_GC;
 
+ loop_rec__:
      PROCESS_MAIN_CHK_LOCKS(c_p);
 
      msgp = PEEK_MESSAGE(c_p);
@@ -1848,6 +1850,7 @@ void process_main(void)
 	 if (ERTS_PROC_PENDING_EXIT(c_p)) {
 	     erts_smp_proc_unlock(c_p, ERTS_PROC_LOCKS_MSG_RECEIVE);
 	     SWAPOUT;
+	     c_p->flags &= ~F_DISABLE_GC;
 	     goto do_schedule; /* Will be rescheduled for exit */
 	 }
 	 ERTS_SMP_MSGQ_MV_INQ2PRIVQ(c_p);
@@ -1857,30 +1860,27 @@ void process_main(void)
 	 else
 #endif
 	 {
+	     c_p->flags &= ~F_DISABLE_GC;
 	     SET_I((BeamInstr *) Arg(0));
 	     Goto(*I);		/* Jump to a wait or wait_timeout instruction */
 	 }
      }
-     ErtsMoveMsgAttachmentIntoProc(msgp, c_p, E, HTOP, FCALLS,
-				   {
-				       SWAPOUT;
-				       PROCESS_MAIN_CHK_LOCKS(c_p);
-				   },
-				   {
-				       ERTS_VERIFY_UNUSED_TEMP_ALLOC(c_p);
-				       PROCESS_MAIN_CHK_LOCKS(c_p);
-				       SWAPIN;
-				   });
      if (is_non_value(ERL_MESSAGE_TERM(msgp))) {
-	 /*
-	  * A corrupt distribution message that we weren't able to decode;
-	  * remove it...
-	  */
-	 ASSERT(!msgp->data.attached);
-         /* TODO: Add DTrace probe for this bad message situation? */
-	 UNLINK_MESSAGE(c_p, msgp);
-	 free_message(msgp);
-	 goto loop_rec__;
+	 SWAPOUT; /* erts_decode_dist_message() may write to heap... */
+	 if (!erts_decode_dist_message(c_p, ERTS_PROC_LOCK_MAIN, msgp, 0)) {
+	     /*
+	      * A corrupt distribution message that we weren't able to decode;
+	      * remove it...
+	      */
+	     /* No swapin should be needed */
+	     ASSERT(HTOP == c_p->htop && E == c_p->stop);
+	     /* TODO: Add DTrace probe for this bad message situation? */
+	     UNLINK_MESSAGE(c_p, msgp);
+	     msgp->next = NULL;
+	     erts_cleanup_messages(msgp);
+	     goto loop_rec__;
+	 }
+	 SWAPIN;
      }
      PreFetch(1, next);
      r(0) = ERL_MESSAGE_TERM(msgp);
@@ -1892,8 +1892,7 @@ void process_main(void)
   */
  OpCase(remove_message): {
      BeamInstr *next;
-     ErlMessage* msgp;
-
+     ErtsMessage* msgp;
      PROCESS_MAIN_CHK_LOCKS(c_p);
 
      PreFetch(0, next);
@@ -1988,11 +1987,21 @@ void process_main(void)
      UNLINK_MESSAGE(c_p, msgp);
      JOIN_MESSAGE(c_p);
      CANCEL_TIMER(c_p);
-     free_message(msgp);
+
+     erts_save_message_in_proc(c_p, msgp);
+     c_p->flags &= ~F_DISABLE_GC;
+
+     if (ERTS_IS_GC_DESIRED_INTERNAL(c_p, HTOP, E)) {
+	 /*
+	  * We want to GC soon but we leave a few
+	  * reductions giving the message some time
+	  * to turn into garbage.
+	  */
+	 ERTS_VBUMP_LEAVE_REDS_INTERNAL(c_p, 5, FCALLS);
+     }
 
      ERTS_VERIFY_UNUSED_TEMP_ALLOC(c_p);
      PROCESS_MAIN_CHK_LOCKS(c_p);
-
      NextPF(0, next);
  }
 
@@ -2001,9 +2010,22 @@ void process_main(void)
      * message didn't match), then jump to the loop_rec instruction.
      */
  OpCase(loop_rec_end_f): {
+
+     ASSERT(c_p->flags & F_DISABLE_GC);
+
      SET_I((BeamInstr *) Arg(0));
      SAVE_MESSAGE(c_p);
-     goto loop_rec__;
+     if (FCALLS > 0 || FCALLS > neg_o_reds) {
+	 FCALLS--;
+	 goto loop_rec__;
+     }
+
+     c_p->flags &= ~F_DISABLE_GC;
+     c_p->i = I;
+     SWAPOUT;
+     c_p->arity = 0;
+     c_p->current = NULL;
+     goto do_schedule;
  }
     /*
      * Prepare to wait for a message or a timeout, whichever occurs first.
@@ -2733,6 +2755,7 @@ do {						\
 	Eterm (*bf)(Process*, Eterm*, BeamInstr*) = GET_BIF_ADDRESS(Arg(0));
 	Eterm result;
 	BeamInstr *next;
+	ErlHeapFragment *live_hf_end;
 
 	PRE_BIF_SWAPOUT(c_p);
 	c_p->fcalls = FCALLS - 1;
@@ -2742,17 +2765,18 @@ do {						\
 	PreFetch(1, next);
 	ASSERT(!ERTS_PROC_IS_EXITING(c_p));
 	ERTS_VERIFY_UNUSED_TEMP_ALLOC(c_p);
+	live_hf_end = c_p->mbuf;
 	result = (*bf)(c_p, reg, I);
 	ASSERT(!ERTS_PROC_IS_EXITING(c_p) || is_non_value(result));
 	ERTS_VERIFY_UNUSED_TEMP_ALLOC(c_p);
 	ERTS_HOLE_CHECK(c_p);
 	ERTS_SMP_REQ_PROC_MAIN_LOCK(c_p);
-	PROCESS_MAIN_CHK_LOCKS(c_p);
-	if (c_p->mbuf || MSO(c_p).overhead >= BIN_VHEAP_SZ(c_p)) {
+	if (ERTS_IS_GC_DESIRED(c_p)) {
 	    Uint arity = ((Export *)Arg(0))->code[2];
-	    result = erts_gc_after_bif_call(c_p, result, reg, arity);
+	    result = erts_gc_after_bif_call_lhf(c_p, live_hf_end, result, reg, arity);
 	    E = c_p->stop;
 	}
+	PROCESS_MAIN_CHK_LOCKS(c_p);
 	HTOP = HEAP_TOP(c_p);
 	FCALLS = c_p->fcalls;
 	if (is_value(result)) {
@@ -2963,6 +2987,9 @@ do {						\
 		     }
 		 }
 		 Op1 = small_to_big(ires, tmp_big);
+#ifdef TAG_LITERAL_PTR
+		 Op1 |= TAG_LITERAL_PTR;
+#endif
 
 	     big_shift:
 		 if (i > 0) {	/* Left shift. */
@@ -3411,9 +3438,6 @@ do {						\
 	 goto do_schedule;
      } else {
 	 ASSERT(!is_value(r(0)));
-	 if (c_p->mbuf) {
-	     erts_garbage_collect(c_p, 0, reg+1, 3);
-	 }
 	 SWAPIN;
 	 Goto(*I);
      }
@@ -3437,6 +3461,7 @@ do {						\
 	     * I[3]: Function pointer to dirty NIF
 	     */
 	    BifFunction vbf;
+	    ErlHeapFragment *live_hf_end;
 
 	    DTRACE_NIF_ENTRY(c_p, (Eterm)I[-3], (Eterm)I[-2], (Uint)I[-1]);
 	    c_p->current = I-3; /* current and vbf set to please handle_error */ 
@@ -3452,6 +3477,7 @@ do {						\
 		NifF* fp = vbf = (NifF*) I[1];
 		struct enif_environment_t env;
 		erts_pre_nif(&env, c_p, (struct erl_module_nif*)I[2]);
+		live_hf_end = c_p->mbuf;
 		nif_bif_result = (*fp)(&env, bif_nif_arity, reg);
 		if (env.exception_thrown)
 		    nif_bif_result = THE_NON_VALUE;
@@ -3494,6 +3520,7 @@ do {						\
 	    {
 		Eterm (*bf)(Process*, Eterm*, BeamInstr*) = vbf;
 		ASSERT(!ERTS_PROC_IS_EXITING(c_p));
+		live_hf_end = c_p->mbuf;
 		nif_bif_result = (*bf)(c_p, reg, I);
 		ASSERT(!ERTS_PROC_IS_EXITING(c_p) ||
 		       is_non_value(nif_bif_result));
@@ -3506,9 +3533,17 @@ do {						\
 	apply_bif_or_nif_epilogue:
 	    ERTS_SMP_REQ_PROC_MAIN_LOCK(c_p);
 	    ERTS_HOLE_CHECK(c_p);
-	    if (c_p->mbuf) {
-		nif_bif_result = erts_gc_after_bif_call(c_p, nif_bif_result,
-						  reg, bif_nif_arity);
+	    /*
+	     * We want to test with ERTS_IS_GC_DESIRED(c_p) in order
+	     * to trigger gc due to binaries based on same conditions
+	     * regardless of how the bif is called. This change will
+	     * however be introduced in a separate commit in order to
+	     * easier identify why the characteristics changed.
+	     */
+	    if (c_p->stop - c_p->htop < c_p->mbuf_sz) {
+		nif_bif_result = erts_gc_after_bif_call_lhf(c_p, live_hf_end,
+							    nif_bif_result,
+							    reg, bif_nif_arity);
 	    }
 	    SWAPIN;  /* There might have been a garbage collection. */
 	    FCALLS = c_p->fcalls;
@@ -6337,13 +6372,6 @@ new_map(Process* p, Eterm* reg, BeamInstr* I)
         erts_factory_proc_init(&factory, p);
         res = erts_hashmap_from_array(&factory, thp, n/2, 0);
         erts_factory_close(&factory);
-        if (p->mbuf) {
-            Uint live = Arg(2);
-            reg[live] = res;
-            erts_garbage_collect(p, 0, reg, live+1);
-            res       = reg[live];
-            E = p->stop;
-        }
         return res;
     }
 
@@ -6409,13 +6437,6 @@ update_map_assoc(Process* p, Eterm* reg, Eterm map, BeamInstr* I)
 	    hx = hashmap_make_hash(new_key);
 
 	    res = erts_hashmap_insert(p, hx, new_key, val, res,  0);
-	    if (p->mbuf) {
-		Uint live = Arg(3);
-		reg[live] = res;
-		erts_garbage_collect(p, 0, reg, live+1);
-		res       = reg[live];
-		E = p->stop;
-	    }
 
 	    new_p += 2;
 	}
@@ -6575,12 +6596,6 @@ update_map_assoc(Process* p, Eterm* reg, Eterm map, BeamInstr* I)
     /* The expensive case, need to build a hashmap */
     if (n > MAP_SMALL_MAP_LIMIT) {
 	res = erts_hashmap_from_ks_and_vs(p,flatmap_get_keys(mp),flatmap_get_values(mp),n);
-	if (p->mbuf) {
-	    Uint live = Arg(3);
-	    reg[live] = res;
-	    erts_garbage_collect(p, 0, reg, live+1);
-	    res       = reg[live];
-	}
     }
     return res;
 }
@@ -6636,14 +6651,6 @@ update_map_exact(Process* p, Eterm* reg, Eterm map, BeamInstr* I)
 		return res;
 	    }
 
-	    if (p->mbuf) {
-		Uint live = Arg(3);
-		reg[live] = res;
-		erts_garbage_collect(p, 0, reg, live+1);
-		res       = reg[live];
-		E = p->stop;
-	    }
-
 	    new_p += 2;
 	}
 	return res;
diff --git a/erts/emulator/beam/beam_load.c b/erts/emulator/beam/beam_load.c
index 1c598601c6..5db971b6af 100644
--- a/erts/emulator/beam/beam_load.c
+++ b/erts/emulator/beam/beam_load.c
@@ -902,7 +902,7 @@ static ErlHeapFragment* new_literal_fragment(Uint size)
     ErlHeapFragment* bp;
     bp = (ErlHeapFragment*) ERTS_HEAP_ALLOC(ERTS_ALC_T_PREPARED_CODE,
 					    ERTS_HEAP_FRAG_SIZE(size));
-    ERTS_INIT_HEAP_FRAG(bp, size);
+    ERTS_INIT_HEAP_FRAG(bp, size, size);
     return bp;
 }
 
@@ -1528,8 +1528,8 @@ read_literal_table(LoaderState* stp)
 	}
 
         if (heap_size > 0) {
-            erts_factory_message_init(&factory, NULL, NULL,
-                                      new_literal_fragment(heap_size));
+            erts_factory_heap_frag_init(&factory,
+					new_literal_fragment(heap_size));
 	    factory.alloc_type = ERTS_ALC_T_PREPARED_CODE;
             val = erts_decode_ext(&factory, &p);
 
@@ -4439,12 +4439,13 @@ freeze_code(LoaderState* stp)
 	code_hdr->literals_start = ptr;
 	code_hdr->literals_end = ptr + stp->total_literal_size;
 	for (i = 0; i < stp->num_literals; i++) {
-            if (stp->literals[i].heap_frags) {
-                move_multi_frags(&ptr, &code_off_heap, stp->literals[i].heap_frags,
-                                 &stp->literals[i].term, 1);
-                ASSERT(erts_is_literal(ptr_val(stp->literals[i].term)));
+            if (is_not_immed(stp->literals[i].term)) {
+                erts_move_multi_frags(&ptr, &code_off_heap,
+				      stp->literals[i].heap_frags,
+				      &stp->literals[i].term, 1, 1);
+                ASSERT(erts_is_literal(stp->literals[i].term,
+				       ptr_val(stp->literals[i].term)));
             }
-            else ASSERT(is_immed(stp->literals[i].term));
 	}
 	code_hdr->literals_off_heap = code_off_heap.first;
 	lp = stp->literal_patches;
diff --git a/erts/emulator/beam/bif.c b/erts/emulator/beam/bif.c
index 453ac74c90..d415603930 100644
--- a/erts/emulator/beam/bif.c
+++ b/erts/emulator/beam/bif.c
@@ -72,7 +72,7 @@ BIF_RETTYPE spawn_3(BIF_ALIST_3)
     ErlSpawnOpts so;
     Eterm pid;
 
-    so.flags = 0;
+    so.flags = erts_default_spo_flags;
     pid = erl_create_process(BIF_P, BIF_ARG_1, BIF_ARG_2, BIF_ARG_3, &so);
     if (is_non_value(pid)) {
 	BIF_ERROR(BIF_P, so.error_code);
@@ -589,7 +589,7 @@ erts_queue_monitor_message(Process *p,
     Eterm reason_copy, ref_copy, item_copy;
     Uint reason_size, ref_size, item_size, heap_size;
     ErlOffHeap *ohp;
-    ErlHeapFragment *bp;
+    ErtsMessage *msgp;
 
     reason_size = IS_CONST(reason) ? 0 : size_object(reason);
     item_size   = IS_CONST(item) ? 0 : size_object(item);
@@ -597,11 +597,8 @@ erts_queue_monitor_message(Process *p,
 
     heap_size = 6+reason_size+ref_size+item_size;
 
-    hp = erts_alloc_message_heap(heap_size,
-				 &bp,
-				 &ohp,
-				 p,
-				 p_locksp);
+    msgp = erts_alloc_message_heap(p, p_locksp, heap_size,
+				   &hp, &ohp);
 
     reason_copy = (IS_CONST(reason)
 		   ? reason
@@ -612,7 +609,7 @@ erts_queue_monitor_message(Process *p,
     ref_copy    = copy_struct(ref, ref_size, &hp, ohp);
 
     tup = TUPLE5(hp, am_DOWN, ref_copy, type, item_copy, reason_copy);
-    erts_queue_message(p, p_locksp, bp, tup, NIL);
+    erts_queue_message(p, p_locksp, msgp, tup, NIL);
 }
 
 static BIF_RETTYPE
@@ -841,7 +838,7 @@ BIF_RETTYPE spawn_link_3(BIF_ALIST_3)
     ErlSpawnOpts so;
     Eterm pid;
 
-    so.flags = SPO_LINK;
+    so.flags = erts_default_spo_flags|SPO_LINK;
     pid = erl_create_process(BIF_P, BIF_ARG_1, BIF_ARG_2, BIF_ARG_3, &so);
     if (is_non_value(pid)) {
 	BIF_ERROR(BIF_P, so.error_code);
@@ -878,7 +875,7 @@ BIF_RETTYPE spawn_opt_1(BIF_ALIST_1)
     /*
      * Store default values for options.
      */
-    so.flags          = SPO_USE_ARGS;
+    so.flags          = erts_default_spo_flags|SPO_USE_ARGS;
     so.min_heap_size  = H_MIN_SIZE;
     so.min_vheap_size = BIN_VH_MIN_SIZE;
     so.priority       = PRIORITY_NORMAL;
@@ -913,6 +910,13 @@ BIF_RETTYPE spawn_opt_1(BIF_ALIST_1)
 		    so.priority = PRIORITY_LOW;
 		else
 		    goto error;
+	    } else if (arg == am_off_heap_message_queue) {
+		if (val == am_true)
+		    so.flags |= SPO_OFF_HEAP_MSGQ;
+		else if (val == am_false)
+		    so.flags &= ~SPO_OFF_HEAP_MSGQ;
+		else
+		    goto error;
 	    } else if (arg == am_min_heap_size && is_small(val)) {
 		Sint min_heap_size = signed_val(val);
 		if (min_heap_size < 0) {
@@ -1691,6 +1695,17 @@ BIF_RETTYPE process_flag_2(BIF_ALIST_2)
        }
        BIF_RET(old_value);
    }
+   else if (BIF_ARG_1 == am_off_heap_message_queue) {
+       int enable;
+       if (BIF_ARG_2 == am_true)
+	   enable = 1;
+       else if (BIF_ARG_2 == am_false)
+	   enable = 0;
+       else
+	   goto error;
+       old_value = erts_change_off_heap_message_queue_state(BIF_P, enable);
+       BIF_RET(old_value);
+   }
    else if (BIF_ARG_1 == am_sensitive) {
        Uint is_sensitive;
        if (BIF_ARG_2 == am_true) {
@@ -1931,7 +1946,7 @@ do_send(Process *p, Eterm to, Eterm msg, Eterm *refp, ErtsSendContext* ctx)
     } else if (is_atom(to)) {
 	Eterm id = erts_whereis_name_to_id(p, to);
 
-	rp = erts_proc_lookup(id);
+	rp = erts_proc_lookup_raw(id);
 	if (rp) {
 	    if (IS_TRACED(p))
 		trace_send(p, to, msg);
@@ -4479,7 +4494,7 @@ BIF_RETTYPE system_flag_2(BIF_ALIST_2)
 	}
     } else if (BIF_ARG_1 == make_small(1)) {
 	int i, max;
-	ErlMessage* mp;
+	ErtsMessage* mp;
 	erts_smp_proc_unlock(BIF_P, ERTS_PROC_LOCK_MAIN);
 	erts_smp_thr_progress_block();
 
diff --git a/erts/emulator/beam/bif.h b/erts/emulator/beam/bif.h
index c6ed60376a..a62eddf36b 100644
--- a/erts/emulator/beam/bif.h
+++ b/erts/emulator/beam/bif.h
@@ -54,22 +54,24 @@ extern Export *erts_convert_time_unit_trap;
 	(p)->fcalls = -CONTEXT_REDS;		\
 } while(0)
 
-
-#define ERTS_VBUMP_ALL_REDS(p)						\
+#define ERTS_VBUMP_ALL_REDS_INTERNAL(p, fcalls)				\
 do {									\
     if (!ERTS_PROC_GET_SAVED_CALLS_BUF((p))) {				\
-	if ((p)->fcalls > 0)						\
-	    ERTS_PROC_GET_SCHDATA((p))->virtual_reds += (p)->fcalls;	\
-	(p)->fcalls = 0;						\
+	if ((fcalls) > 0)						\
+	    ERTS_PROC_GET_SCHDATA((p))->virtual_reds += (fcalls);	\
+	(fcalls) = 0;							\
     }									\
     else {								\
-	if ((p)->fcalls > -CONTEXT_REDS)				\
+	if ((fcalls) > -CONTEXT_REDS)					\
 	    ERTS_PROC_GET_SCHDATA((p))->virtual_reds			\
-		+= ((p)->fcalls - (-CONTEXT_REDS));			\
-	(p)->fcalls = -CONTEXT_REDS;					\
+		+= ((fcalls) - (-CONTEXT_REDS));			\
+	(fcalls) = -CONTEXT_REDS;					\
     }									\
 } while(0)
 
+#define ERTS_VBUMP_ALL_REDS(p) \
+    ERTS_VBUMP_ALL_REDS_INTERNAL((p), (p)->fcalls)
+
 #define BUMP_REDS(p, gc) do {			   \
      ASSERT(p);		 			   \
      ERTS_SMP_LC_ASSERT(ERTS_PROC_LOCK_MAIN & erts_proc_lc_my_proc_locks(p));\
@@ -110,10 +112,34 @@ do {									\
     }									\
 } while(0)
 
-#define ERTS_BIF_REDS_LEFT(p)						\
+#define ERTS_VBUMP_LEAVE_REDS_INTERNAL(P, Reds, FCalls)			\
+    do {								\
+	if (ERTS_PROC_GET_SAVED_CALLS_BUF((P))) {			\
+	    int nreds__ = ((int)(Reds)) - CONTEXT_REDS;			\
+	    if ((FCalls) > nreds__) {					\
+		ERTS_PROC_GET_SCHDATA((P))->virtual_reds		\
+		    += (FCalls) - nreds__;				\
+		(FCalls) = nreds__;					\
+	    }								\
+	}								\
+	else {								\
+	    if ((FCalls) > (Reds)) {					\
+		ERTS_PROC_GET_SCHDATA((P))->virtual_reds		\
+		    += (FCalls) - (Reds);				\
+		(FCalls) = (Reds);					\
+	    }								\
+	}								\
+    } while (0)
+
+#define ERTS_VBUMP_LEAVE_REDS(P, Reds)					\
+    ERTS_VBUMP_LEAVE_REDS_INTERNAL(P, Reds, (P)->fcalls)
+
+#define ERTS_REDS_LEFT(p, FCalls)					\
   (ERTS_PROC_GET_SAVED_CALLS_BUF((p))					\
-   ? ((p)->fcalls > -CONTEXT_REDS ? ((p)->fcalls - (-CONTEXT_REDS)) : 0)\
-   : ((p)->fcalls > 0 ? (p)->fcalls : 0))
+   ? ((FCalls) > -CONTEXT_REDS ? ((FCalls) - (-CONTEXT_REDS)) : 0)	\
+   : ((FCalls) > 0 ? (FCalls) : 0))
+
+#define ERTS_BIF_REDS_LEFT(p) ERTS_REDS_LEFT(p, p->fcalls)
 
 #define BIF_RET2(x, gc) do {			\
     BUMP_REDS(BIF_P, (gc));			\
diff --git a/erts/emulator/beam/break.c b/erts/emulator/beam/break.c
index d90aed203e..2c8ecf04be 100644
--- a/erts/emulator/beam/break.c
+++ b/erts/emulator/beam/break.c
@@ -252,7 +252,7 @@ print_process_info(int to, void *to_arg, Process *p)
 
     /* display the message queue only if there is anything in it */
     if (!ERTS_IS_CRASH_DUMPING && p->msg.first != NULL && !garbing) {
-	ErlMessage* mp;
+	ErtsMessage* mp;
 	erts_print(to, to_arg, "Message queue: [");
 	for (mp = p->msg.first; mp; mp = mp->next)
 	    erts_print(to, to_arg, mp->next ? "%T," : "%T", ERL_MESSAGE_TERM(mp));
@@ -323,7 +323,7 @@ print_process_info(int to, void *to_arg, Process *p)
     erts_print(to, to_arg, "Heap unused: %bpu\n", (p->hend - p->htop));
     erts_print(to, to_arg, "OldHeap unused: %bpu\n",
 	       (OLD_HEAP(p) == NULL) ? 0 : (OLD_HEND(p) - OLD_HTOP(p)) );
-    erts_print(to, to_arg, "Memory: %beu\n", erts_process_memory(p));
+    erts_print(to, to_arg, "Memory: %beu\n", erts_process_memory(p, !0));
 
     if (garbing) {
 	print_garb_info(to, to_arg, p);
diff --git a/erts/emulator/beam/copy.c b/erts/emulator/beam/copy.c
index ec769c3b49..f27c526413 100644
--- a/erts/emulator/beam/copy.c
+++ b/erts/emulator/beam/copy.c
@@ -35,7 +35,7 @@
 #include "erl_bits.h"
 #include "dtrace-wrapper.h"
 
-static void move_one_frag(Eterm** hpp, ErlHeapFragment*, ErlOffHeap*);
+static void move_one_frag(Eterm** hpp, ErlHeapFragment*, ErlOffHeap*, int);
 
 /*
  *  Copy object "obj" to process p.
@@ -279,7 +279,7 @@ Eterm copy_struct(Eterm obj, Uint sz, Eterm** hpp, ErlOffHeap* off_heap)
 	    break;
 	case TAG_PRIMARY_LIST:
 	    objp = list_val(obj);
-	    if (in_area(objp,hstart,hsize)) {
+	    if (ErtsInArea(objp,hstart,hsize)) {
 		hp++;
 		break;
 	    }
@@ -318,7 +318,7 @@ Eterm copy_struct(Eterm obj, Uint sz, Eterm** hpp, ErlOffHeap* off_heap)
 	    }
 	    
 	case TAG_PRIMARY_BOXED:
-	    if (in_area(boxed_val(obj),hstart,hsize)) {
+	    if (ErtsInArea(boxed_val(obj),hstart,hsize)) {
 		hp++;
 		break;
 	    }
@@ -621,17 +621,24 @@ Eterm copy_shallow(Eterm* ptr, Uint sz, Eterm** hpp, ErlOffHeap* off_heap)
  * move markers.
  * Typically used to copy a multi-fragmented message (from NIF).
  */
-void move_multi_frags(Eterm** hpp, ErlOffHeap* off_heap, ErlHeapFragment* first,
-		      Eterm* refs, unsigned nrefs)
+void erts_move_multi_frags(Eterm** hpp, ErlOffHeap* off_heap, ErlHeapFragment* first,
+			   Eterm* refs, unsigned nrefs, int literals)
 {
     ErlHeapFragment* bp;
     Eterm* hp_start = *hpp;
     Eterm* hp_end;
     Eterm* hp;
     unsigned i;
+    Eterm literal_tag;
+
+#ifdef TAG_LITERAL_PTR
+    literal_tag = (Eterm) literals ? TAG_LITERAL_PTR : 0;
+#else
+    literal_tag = (Eterm) 0;
+#endif
 
     for (bp=first; bp!=NULL; bp=bp->next) {
-	move_one_frag(hpp, bp, off_heap);
+	move_one_frag(hpp, bp, off_heap, literals);
     }
     hp_end = *hpp;
     for (hp=hp_start; hp<hp_end; ++hp) {
@@ -644,6 +651,9 @@ void move_multi_frags(Eterm** hpp, ErlOffHeap* off_heap, ErlHeapFragment* first,
 	    val = *ptr;
 	    if (IS_MOVED_BOXED(val)) {
 		ASSERT(is_boxed(val));
+#ifdef TAG_LITERAL_PTR
+		val |= literal_tag;
+#endif
 		*hp = val;
 	    }
 	    break;
@@ -651,7 +661,11 @@ void move_multi_frags(Eterm** hpp, ErlOffHeap* off_heap, ErlHeapFragment* first,
 	    ptr = list_val(gval);
 	    val = *ptr;
 	    if (IS_MOVED_CONS(val)) {
-		*hp = ptr[1];
+		val = ptr[1];
+#ifdef TAG_LITERAL_PTR
+		val |= literal_tag;
+#endif
+		*hp = val;
 	    }
 	    break;
 	case TAG_PRIMARY_HEADER:
@@ -662,12 +676,12 @@ void move_multi_frags(Eterm** hpp, ErlOffHeap* off_heap, ErlHeapFragment* first,
 	}
     }
     for (i=0; i<nrefs; ++i) {
-	refs[i] = follow_moved(refs[i]);
+	refs[i] = follow_moved(refs[i], literal_tag);
     }
 }
 
 static void
-move_one_frag(Eterm** hpp, ErlHeapFragment* frag, ErlOffHeap* off_heap)
+move_one_frag(Eterm** hpp, ErlHeapFragment* frag, ErlOffHeap* off_heap, int literals)
 {
     Eterm* ptr = frag->mem;
     Eterm* end = ptr + frag->used_size;
@@ -704,4 +718,3 @@ move_one_frag(Eterm** hpp, ErlHeapFragment* frag, ErlOffHeap* off_heap)
     OH_OVERHEAD(off_heap, frag->off_heap.overhead);
     frag->off_heap.first = NULL;
 }
-
diff --git a/erts/emulator/beam/dist.c b/erts/emulator/beam/dist.c
index 10dd6cf206..68745fc448 100644
--- a/erts/emulator/beam/dist.c
+++ b/erts/emulator/beam/dist.c
@@ -378,10 +378,11 @@ static void doit_node_link_net_exits(ErtsLink *lnk, void *vnecp)
     ASSERT(lnk->type == LINK_NODE);
     if (is_internal_pid(lnk->pid)) {
 	ErtsProcLocks rp_locks = ERTS_PROC_LOCK_LINK;
-	rp = erts_pid2proc(NULL, 0, lnk->pid, rp_locks);
-	if (!rp) {
+	ErlOffHeap *ohp;
+	rp = erts_proc_lookup(lnk->pid);
+	if (!rp)
 	    goto done;
-	}
+	erts_smp_proc_lock(rp, rp_locks);
 	rlnk = erts_remove_link(&ERTS_P_LINKS(rp), name);
 	if (rlnk != NULL) {
 	    ASSERT(is_atom(rlnk->pid) && (rlnk->type == LINK_NODE));
@@ -389,12 +390,14 @@ static void doit_node_link_net_exits(ErtsLink *lnk, void *vnecp)
 	}
 	n = ERTS_LINK_REFC(lnk);
 	for (i = 0; i < n; ++i) {
-	    ErlHeapFragment* bp;
-	    ErlOffHeap *ohp;
 	    Eterm tup;
-	    Eterm *hp = erts_alloc_message_heap(3,&bp,&ohp,rp,&rp_locks);
+	    Eterm *hp;
+	    ErtsMessage *msgp;
+
+	    msgp = erts_alloc_message_heap(rp, &rp_locks,
+					   3, &hp, &ohp);
 	    tup = TUPLE2(hp, am_nodedown, name);
-	    erts_queue_message(rp, &rp_locks, bp, tup, NIL);
+	    erts_queue_message(rp, &rp_locks, msgp, tup, NIL);
 	}
 	erts_smp_proc_unlock(rp, rp_locks);
     }
@@ -1462,7 +1465,7 @@ int erts_net_message(Port *prt,
 		ErlOffHeap *ohp;
 		ASSERT(xsize);
 		heap_frag = erts_dist_ext_trailer(ede_copy);
-		ERTS_INIT_HEAP_FRAG(heap_frag, token_size);
+		ERTS_INIT_HEAP_FRAG(heap_frag, token_size, token_size);
 		hp = heap_frag->mem;
 		ohp = &heap_frag->off_heap;
 		token = tuple[5];
@@ -1511,7 +1514,7 @@ int erts_net_message(Port *prt,
 		ErlOffHeap *ohp;
 		ASSERT(xsize);
 		heap_frag = erts_dist_ext_trailer(ede_copy);
-		ERTS_INIT_HEAP_FRAG(heap_frag, token_size);
+		ERTS_INIT_HEAP_FRAG(heap_frag, token_size, token_size);
 		hp = heap_frag->mem;
 		ohp = &heap_frag->off_heap;
 		token = tuple[4];
@@ -3271,11 +3274,16 @@ send_nodes_mon_msg(Process *rp,
 		   Uint sz)
 {
     Eterm msg;
-    ErlHeapFragment* bp;
+    Eterm *hp;
+    ErtsMessage *mp;
     ErlOffHeap *ohp;
-    Eterm *hp = erts_alloc_message_heap(sz, &bp, &ohp, rp, rp_locksp);
 #ifdef DEBUG
-    Eterm *hend = hp + sz;
+    Eterm *hend;
+#endif
+
+    mp = erts_alloc_message_heap(rp, rp_locksp, sz, &hp, &ohp);
+#ifdef DEBUG
+    hend = hp + sz;
 #endif
 
     if (!nmp->opts) {
@@ -3321,7 +3329,7 @@ send_nodes_mon_msg(Process *rp,
     }
 
     ASSERT(hend == hp);
-    erts_queue_message(rp, rp_locksp, bp, msg, NIL);
+    erts_queue_message(rp, rp_locksp, mp, msg, NIL);
 }
 
 static void
diff --git a/erts/emulator/beam/erl_alloc.c b/erts/emulator/beam/erl_alloc.c
index 3e300f88ea..019aa0f16c 100644
--- a/erts/emulator/beam/erl_alloc.c
+++ b/erts/emulator/beam/erl_alloc.c
@@ -582,7 +582,7 @@ erts_alloc_init(int *argc, char **argv, ErtsAllocInitOpts *eaiop)
     fix_type_sizes[ERTS_ALC_FIX_TYPE_IX(ERTS_ALC_T_DRV_SEL_D_STATE)]
 	= sizeof(ErtsDrvSelectDataState);
     fix_type_sizes[ERTS_ALC_FIX_TYPE_IX(ERTS_ALC_T_MSG_REF)]
-	= sizeof(ErlMessage);
+	= sizeof(ErtsMessageRef);
 #ifdef ERTS_SMP
     fix_type_sizes[ERTS_ALC_FIX_TYPE_IX(ERTS_ALC_T_THR_Q_EL_SL)]
 	= sizeof(ErtsThrQElement_t);
@@ -2916,12 +2916,12 @@ reply_alloc_info(void *vair)
     int global_instances = air->req_sched == sched_id;
     ErtsProcLocks rp_locks;
     Process *rp = air->proc;
-    Eterm ref_copy = NIL, ai_list, msg;
-    Eterm *hp = NULL, *hp_end = NULL, *hp_start = NULL;
+    Eterm ref_copy = NIL, ai_list, msg = NIL;
+    Eterm *hp = NULL, *hp_start = NULL, *hp_end = NULL;
     Eterm **hpp;
     Uint sz, *szp;
     ErlOffHeap *ohp = NULL;
-    ErlHeapFragment *bp = NULL;
+    ErtsMessage *mp = NULL;
     struct erts_mmap_info_struct emis;
     int i;
     Eterm (*info_func)(Allctr_t *,
@@ -3123,20 +3123,17 @@ reply_alloc_info(void *vair)
 	if (hpp)
 	    break;
 
-	hp = erts_alloc_message_heap(sz, &bp, &ohp, rp, &rp_locks);
+	mp = erts_alloc_message_heap(rp, &rp_locks, sz, &hp, &ohp);
 	hp_start = hp;
 	hp_end = hp + sz;
 	szp = NULL;
 	hpp = &hp;
     }
-    if (bp)
-	bp = erts_resize_message_buffer(bp, hp - hp_start, &msg, 1);
-    else {
-	ASSERT(hp);
-	HRelease(rp, hp_end, hp);	    
-    }
 
-    erts_queue_message(rp, &rp_locks, bp, msg, NIL);
+    if (hp != hp_end)
+	erts_shrink_message_heap(&mp, rp, hp_start, hp, hp_end, &msg, 1);
+
+    erts_queue_message(rp, &rp_locks, mp, msg, NIL);
 
     if (air->req_sched == sched_id)
 	rp_locks &= ~ERTS_PROC_LOCK_MAIN;
diff --git a/erts/emulator/beam/erl_alloc.h b/erts/emulator/beam/erl_alloc.h
index a0d8561e84..14e80960f5 100644
--- a/erts/emulator/beam/erl_alloc.h
+++ b/erts/emulator/beam/erl_alloc.h
@@ -44,9 +44,11 @@
 #if ERTS_CAN_INLINE && ERTS_ALC_WANT_INLINE
 #  define ERTS_ALC_DO_INLINE 1
 #  define ERTS_ALC_INLINE static ERTS_INLINE
+#  define ERTS_ALC_FORCE_INLINE static ERTS_FORCE_INLINE
 #else
 #  define ERTS_ALC_DO_INLINE 0
 #  define ERTS_ALC_INLINE
+#  define ERTS_ALC_FORCE_INLINE
 #endif
 
 #define ERTS_ALC_NO_FIXED_SIZES \
@@ -178,6 +180,12 @@ void  sys_free(void *)               __deprecated; /* erts_free()        */
 void *sys_alloc(Uint )               __deprecated; /* erts_alloc_fnf()   */
 void *sys_realloc(void *, Uint)      __deprecated; /* erts_realloc_fnf() */
 
+#undef ERTS_HAVE_IS_IN_LITERAL_RANGE
+#if defined(ARCH_32) || defined(ERTS_HAVE_OS_PHYSICAL_MEMORY_RESERVATION)
+#  define ERTS_HAVE_IS_IN_LITERAL_RANGE
+#endif
+
+
 /*
  * erts_alloc[_fnf](), erts_realloc[_fnf](), erts_free() works as
  * malloc(), realloc(), and free() with the following exceptions:
@@ -205,7 +213,9 @@ void erts_free(ErtsAlcType_t type, void *ptr);
 void *erts_alloc_fnf(ErtsAlcType_t type, Uint size);
 void *erts_realloc_fnf(ErtsAlcType_t type, void *ptr, Uint size);
 int erts_is_allctr_wrapper_prelocked(void);
-int erts_is_literal(void* ptr);
+#ifdef ERTS_HAVE_IS_IN_LITERAL_RANGE
+int erts_is_in_literal_range(void* ptr);
+#endif
 
 #endif /* #if !ERTS_ALC_DO_INLINE */
 
@@ -283,8 +293,10 @@ int erts_is_allctr_wrapper_prelocked(void)
 	&& !!erts_tsd_get(erts_allctr_prelock_tsd_key);  /* by me  */
 }
 
-ERTS_ALC_INLINE
-int erts_is_literal(void* ptr)
+#ifdef ERTS_HAVE_IS_IN_LITERAL_RANGE
+
+ERTS_ALC_FORCE_INLINE
+int erts_is_in_literal_range(void* ptr)
 {
 #if defined(ARCH_32)
     Uint ix = (UWord)ptr >> ERTS_MMAP_SUPERALIGNED_BITS;
@@ -293,18 +305,16 @@ int erts_is_literal(void* ptr)
                   & ((UWord)1 << (ix % ERTS_VSPACE_WORD_BITS));
 
 #elif defined(ARCH_64)
-# if defined(ERTS_HAVE_OS_PHYSICAL_MEMORY_RESERVATION)
     extern char* erts_literals_start;
     extern UWord erts_literals_size;
     return ErtsInArea(ptr, erts_literals_start, erts_literals_size);
-# else
-#  error Do the tag thing
-# endif
 #else
 # error No ARCH_xx
 #endif
 }
 
+#endif /* ERTS_HAVE_IS_IN_LITERAL_RANGE */
+
 #endif /* #if ERTS_ALC_DO_INLINE || defined(ERTS_ALC_INTERNAL__) */
 
 #define ERTS_ALC_GET_THR_IX() ((int) erts_get_scheduler_id())
diff --git a/erts/emulator/beam/erl_alloc.types b/erts/emulator/beam/erl_alloc.types
index 7d519c1be4..75b4913012 100644
--- a/erts/emulator/beam/erl_alloc.types
+++ b/erts/emulator/beam/erl_alloc.types
@@ -152,6 +152,8 @@ type	OLD_HEAP	EHEAP		PROCESSES	old_heap
 type	HEAP_FRAG	EHEAP		PROCESSES	heap_frag
 type	TMP_HEAP	TEMPORARY	PROCESSES	tmp_heap
 type	MSG_REF		FIXED_SIZE	PROCESSES	msg_ref
+type	MSG		EHEAP		PROCESSES	message
+type	MSGQ_CHNG	SHORT_LIVED	PROCESSES	messages_queue_change
 type	MSG_ROOTS	TEMPORARY	PROCESSES	msg_roots
 type	ROOTSET		TEMPORARY	PROCESSES	root_set
 type	LOADER_TMP	TEMPORARY	CODE		loader_tmp
diff --git a/erts/emulator/beam/erl_bif_ddll.c b/erts/emulator/beam/erl_bif_ddll.c
index 28bec6325c..2b1d875bfe 100644
--- a/erts/emulator/beam/erl_bif_ddll.c
+++ b/erts/emulator/beam/erl_bif_ddll.c
@@ -1707,18 +1707,19 @@ static void notify_proc(Process *proc, Eterm ref, Eterm driver_name, Eterm type,
     Eterm mess;
     Eterm r;
     Eterm *hp;
-    ErlHeapFragment *bp;
-    ErlOffHeap *ohp;
+    ErtsMessage *mp;
     ErtsProcLocks rp_locks = 0;
+    ErlOffHeap *ohp;
     ERTS_SMP_CHK_NO_PROC_LOCKS;
 
     assert_drv_list_rwlocked();
     if (errcode != 0) {
 	int need = load_error_need(errcode);
 	Eterm e;
-	hp = erts_alloc_message_heap(6 /* tuple */ + 3 /* Error tuple */ + 
-				     REF_THING_SIZE + need, &bp, &ohp, 
-				     proc, &rp_locks);
+	mp = erts_alloc_message_heap(proc, &rp_locks,
+				     (6 /* tuple */ + 3 /* Error tuple */ + 
+				      REF_THING_SIZE + need),
+				     &hp, &ohp);
 	r = copy_ref(ref,hp);
 	hp += REF_THING_SIZE;
 	e = build_load_error_hp(hp, errcode);
@@ -1727,12 +1728,14 @@ static void notify_proc(Process *proc, Eterm ref, Eterm driver_name, Eterm type,
 	hp += 3;
 	mess = TUPLE5(hp,type,r,am_driver,driver_name,mess);
     } else {	
-	hp = erts_alloc_message_heap(6 /* tuple */ + REF_THING_SIZE, &bp, &ohp, proc, &rp_locks);
+	mp = erts_alloc_message_heap(proc, &rp_locks,
+				     6 /* tuple */ + REF_THING_SIZE,
+				     &hp, &ohp);
 	r = copy_ref(ref,hp);
 	hp += REF_THING_SIZE;
 	mess = TUPLE5(hp,type,r,am_driver,driver_name,tag);
     }
-    erts_queue_message(proc, &rp_locks, bp, mess, am_undefined);
+    erts_queue_message(proc, &rp_locks, mp, mess, am_undefined);
     erts_smp_proc_unlock(proc, rp_locks);
     ERTS_SMP_CHK_NO_PROC_LOCKS;
 }
diff --git a/erts/emulator/beam/erl_bif_info.c b/erts/emulator/beam/erl_bif_info.c
index a73ad826db..1eb106a551 100644
--- a/erts/emulator/beam/erl_bif_info.c
+++ b/erts/emulator/beam/erl_bif_info.c
@@ -589,6 +589,7 @@ static Eterm pi_args[] = {
     am_min_bin_vheap_size,
     am_current_location,
     am_current_stacktrace,
+    am_off_heap_message_queue
 };
 
 #define ERTS_PI_ARGS ((int) (sizeof(pi_args)/sizeof(Eterm)))
@@ -636,6 +637,7 @@ pi_arg2ix(Eterm arg)
     case am_min_bin_vheap_size:			return 28;
     case am_current_location:			return 29;
     case am_current_stacktrace:			return 30;
+    case am_off_heap_message_queue:		return 31;
     default:					return -1;
     }
 }
@@ -718,9 +720,10 @@ pi_pid2proc(Process *c_p, Eterm pid, ErtsProcLocks info_locks)
 
 
 
-BIF_RETTYPE
+static BIF_RETTYPE
 process_info_aux(Process *BIF_P,
 		 Process *rp,
+		 ErtsProcLocks rp_locks,
 		 Eterm rpid,
 		 Eterm item,
 		 int always_wrap);
@@ -811,10 +814,31 @@ process_info_list(Process *c_p, Eterm pid, Eterm list, int always_wrap,
 	*fail_type = ERTS_PI_FAIL_TYPE_AWAIT_EXIT;
 	goto done;
     }
-    else if (!(locks & ERTS_PROC_LOCK_STATUS)) {
-	erts_smp_proc_unlock(rp, ERTS_PROC_LOCK_STATUS);
+    else {
+	ErtsProcLocks unlock_locks = 0;
+
+	if (c_p == rp)
+	    locks |= ERTS_PROC_LOCK_MAIN;
+
+	if (!(locks & ERTS_PROC_LOCK_STATUS))
+	    unlock_locks |= ERTS_PROC_LOCK_STATUS;
+
+	if (locks & ERTS_PROC_LOCK_MSGQ) {
+	    /*
+	     * Move in queue into private queue and
+	     * release msgq lock, enabling others to
+	     * send messages to the process while it
+	     * is being inspected...
+	     */
+	    ASSERT(locks & ERTS_PROC_LOCK_MAIN);
+	    ERTS_SMP_MSGQ_MV_INQ2PRIVQ(rp);
+	    locks &= ~ERTS_PROC_LOCK_MSGQ;
+	    unlock_locks |= ERTS_PROC_LOCK_MSGQ;
+	}
+
+	if (unlock_locks)
+	    erts_smp_proc_unlock(rp, unlock_locks);
     }
-	
 
     /*
      * We always handle 'messages' first if it should be part
@@ -826,7 +850,7 @@ process_info_list(Process *c_p, Eterm pid, Eterm list, int always_wrap,
     if (want_messages) {
 	ix = pi_arg2ix(am_messages);
 	ASSERT(part_res[ix] == THE_NON_VALUE);
-	part_res[ix] = process_info_aux(c_p, rp, pid, am_messages, always_wrap);
+	part_res[ix] = process_info_aux(c_p, rp, locks, pid, am_messages, always_wrap);
 	ASSERT(part_res[ix] != THE_NON_VALUE);
     }
 
@@ -834,7 +858,7 @@ process_info_list(Process *c_p, Eterm pid, Eterm list, int always_wrap,
 	ix = res_elem_ix[res_elem_ix_ix];
 	if (part_res[ix] == THE_NON_VALUE) {
 	    arg = pi_ix2arg(ix);
-	    part_res[ix] = process_info_aux(c_p, rp, pid, arg, always_wrap);
+	    part_res[ix] = process_info_aux(c_p, rp, locks, pid, arg, always_wrap);
 	    ASSERT(part_res[ix] != THE_NON_VALUE);
 	}
     }
@@ -965,9 +989,31 @@ BIF_RETTYPE process_info_2(BIF_ALIST_2)
 	ERTS_BIF_AWAIT_X_DATA_TRAP(BIF_P, BIF_ARG_1, am_undefined);
     }
     else {
+	ErtsProcLocks unlock_locks = 0;
+
+	if (BIF_P == rp)
+	    info_locks |= ERTS_PROC_LOCK_MAIN;
+
 	if (!(info_locks & ERTS_PROC_LOCK_STATUS))
-	    erts_smp_proc_unlock(rp, ERTS_PROC_LOCK_STATUS);
-	res = process_info_aux(BIF_P, rp, pid, BIF_ARG_2, 0);
+	    unlock_locks |= ERTS_PROC_LOCK_STATUS;
+
+	if (info_locks & ERTS_PROC_LOCK_MSGQ) {
+	    /*
+	     * Move in queue into private queue and
+	     * release msgq lock, enabling others to
+	     * send messages to the process while it
+	     * is being inspected...
+	     */
+	    ASSERT(info_locks & ERTS_PROC_LOCK_MAIN);
+	    ERTS_SMP_MSGQ_MV_INQ2PRIVQ(rp);
+	    info_locks &= ~ERTS_PROC_LOCK_MSGQ;
+	    unlock_locks |= ERTS_PROC_LOCK_MSGQ;
+	}
+
+	if (unlock_locks)
+	    erts_smp_proc_unlock(rp, unlock_locks);
+
+	res = process_info_aux(BIF_P, rp, info_locks, pid, BIF_ARG_2, 0);
     }
     ASSERT(is_value(res));
 
@@ -985,6 +1031,7 @@ BIF_RETTYPE process_info_2(BIF_ALIST_2)
 Eterm
 process_info_aux(Process *BIF_P,
 		 Process *rp,
+		 ErtsProcLocks rp_locks,
 		 Eterm rpid,
 		 Eterm item,
 		 int always_wrap)
@@ -1056,171 +1103,55 @@ process_info_aux(Process *BIF_P,
 	break;
 
     case am_messages: {
-	ErlMessage* mp;
-	int n;
-
-	ERTS_SMP_MSGQ_MV_INQ2PRIVQ(rp);
-	n = rp->msg.len;
 
-	if (n == 0 || ERTS_TRACE_FLAGS(rp) & F_SENSITIVE) {
+	if (rp->msg.len == 0 || ERTS_TRACE_FLAGS(rp) & F_SENSITIVE) {
 	    hp = HAlloc(BIF_P, 3);
 	} else {
-	    int remove_bad_messages = 0;
-	    struct {
-		Uint copy_struct_size;
-		ErlMessage* msgp;
-	    } *mq = erts_alloc(ERTS_ALC_T_TMP, n*sizeof(*mq));
-	    Sint i = 0;
-	    Uint heap_need = 3;
+	    ErtsMessageInfo *mip;
+	    Sint i;
+	    Uint heap_need;
+#ifdef DEBUG
 	    Eterm *hp_end;
+#endif
 
-	    for (mp = rp->msg.first; mp; mp = mp->next) {
-		heap_need += 2;
-		mq[i].msgp = mp;
-		if (rp != BIF_P) {
-		    Eterm msg = ERL_MESSAGE_TERM(mq[i].msgp);
-		    if (is_value(msg)) {
-			mq[i].copy_struct_size = (is_immed(msg)? 0 :
-						  size_object(msg));
-		    }
-		    else if (mq[i].msgp->data.attached) {
-			mq[i].copy_struct_size
-			    = erts_msg_attached_data_size(mq[i].msgp);
-		    }
-		    else {
-			/* Bad distribution message; ignore */
-			remove_bad_messages = 1;
-			mq[i].copy_struct_size = 0;
-		    }
-		    heap_need += mq[i].copy_struct_size;
-		}
-		else {
-		    mq[i].copy_struct_size = mp->data.attached ?
-                        erts_msg_attached_data_size(mp) : 0;
-		}
-		i++;
-	    }
+	    mip = erts_alloc(ERTS_ALC_T_TMP,
+			     rp->msg.len*sizeof(ErtsMessageInfo));
 
-            if (rp != BIF_P) {
-                hp = HAlloc(BIF_P, heap_need);
-                hp_end = hp + heap_need;
-                ASSERT(i == n);
-                for (i--; i >= 0; i--) {
-                    Eterm msg = ERL_MESSAGE_TERM(mq[i].msgp);
-		    if (is_value(msg)) {
-			if (mq[i].copy_struct_size)
-			    msg = copy_struct(msg,
-					      mq[i].copy_struct_size,
-					      &hp,
-					      &MSO(BIF_P));
-		    }
-		    else if (mq[i].msgp->data.attached) {
-			ErlHeapFragment *hfp;
-			/*
-			 * Decode it into a message buffer and attach it
-			 * to the message instead of the attached external
-			 * term.
-			 *
-			 * Note that we may not pass a process pointer
-			 * to erts_msg_distext2heap(), since it would then
-			 * try to alter locks on that process.
-			 */
-			msg = erts_msg_distext2heap(
-			    NULL, NULL, &hfp, &ERL_MESSAGE_TOKEN(mq[i].msgp),
-			    mq[i].msgp->data.dist_ext);
-
-			ERL_MESSAGE_TERM(mq[i].msgp) = msg;
-			mq[i].msgp->data.heap_frag = hfp;
-
-			if (is_non_value(msg)) {
-			    ASSERT(!mq[i].msgp->data.heap_frag);
-			    /* Bad distribution message; ignore */
-			    remove_bad_messages = 1;
-			    continue;
-			}
-			else {
-			    /* Make our copy of the message */
-			    ASSERT(size_object(msg) == erts_used_frag_sz(hfp));
-			    msg = copy_struct(msg,
-					      erts_used_frag_sz(hfp),
-					      &hp,
-					      &MSO(BIF_P));
-			}
-		    }
-		    else {
-			/* Bad distribution message; ignore */
-			remove_bad_messages = 1;
-			continue;
-		    }
-                    res = CONS(hp, msg, res);
-                    hp += 2;
-		}
-                HRelease(BIF_P, hp_end, hp+3);
-            }
-	    else {
-                for (i--; i >= 0; i--) {
-                    ErtsHeapFactory factory;
-                    Eterm msg = ERL_MESSAGE_TERM(mq[i].msgp);
-
-                    erts_factory_proc_prealloc_init(&factory, BIF_P,
-                                                    mq[i].copy_struct_size+2);
-		    if (mq[i].msgp->data.attached) {
-			/* Decode it on the heap */
-			erts_move_msg_attached_data_to_heap(&factory,
-							    mq[i].msgp);
-			msg = ERL_MESSAGE_TERM(mq[i].msgp);
-			ASSERT(!mq[i].msgp->data.attached);
-                    }
-                    if (is_value(msg)) {
-                        hp = erts_produce_heap(&factory, 2, 0);
-                        res = CONS(hp, msg, res);
-                    }
-                    else {
-                        /* Bad distribution message; ignore */
-                        remove_bad_messages = 1;
-                        continue;
-                    }
-                    erts_factory_close(&factory);
-		}
-                hp = HAlloc(BIF_P, 3);
-	    }
-	    erts_free(ERTS_ALC_T_TMP, mq);
-	    if (remove_bad_messages) {
-		ErlMessage **mpp;
-		/*
-		 * We need to remove bad distribution messages from
-		 * the queue, so that the value returned for
-		 * 'message_queue_len' is consistent with the value
-		 * returned for 'messages'.
-		 */
-		mpp = &rp->msg.first;
-		mp = rp->msg.first;
-		while (mp) {
-		    if (is_value(ERL_MESSAGE_TERM(mp))) {
-			mpp = &mp->next;
-			mp = mp->next;
-		    }
-		    else {
-			ErlMessage* bad_mp = mp;
-			ASSERT(!mp->data.attached);
-			if (rp->msg.save == &mp->next)
-			    rp->msg.save = mpp;
-			if (rp->msg.last == &mp->next)
-			    rp->msg.last = mpp;
-			*mpp = mp->next;
-			mp = mp->next;
-			rp->msg.len--;
-			free_message(bad_mp);
-		    }
-		}
+	    /*
+	     * Note that message queue may shrink when calling
+	     * erts_prep_msgq_for_inspection() since it removes
+	     * corrupt distribution messages.
+	     */
+	    heap_need = erts_prep_msgq_for_inspection(BIF_P, rp, rp_locks, mip);
+	    heap_need += 3; /* top 2-tuple */
+	    heap_need += rp->msg.len*2; /* Cons cells */
+
+	    hp = HAlloc(BIF_P, heap_need); /* heap_need is exact */
+#ifdef DEBUG
+	    hp_end = hp + heap_need;
+#endif
+
+	    /* Build list of messages... */
+	    for (i = rp->msg.len - 1, res = NIL; i >= 0; i--) {
+		Eterm msg = ERL_MESSAGE_TERM(mip[i].msgp);
+		Uint sz = mip[i].size;
+
+		if (sz != 0)
+		    msg = copy_struct(msg, sz, &hp, &BIF_P->off_heap);
+
+		res = CONS(hp, msg, res);
+		hp += 2;
 	    }
+
+	    ASSERT(hp_end == hp + 3);
+
+	    erts_free(ERTS_ALC_T_TMP, mip);
 	}
 	break;
     }
 
     case am_message_queue_len:
 	hp = HAlloc(BIF_P, 3);
-	ERTS_SMP_MSGQ_MV_INQ2PRIVQ(rp);
 	res = make_small(rp->msg.len);
 	break;
 
@@ -1408,7 +1339,7 @@ process_info_aux(Process *BIF_P,
     }
 
     case am_total_heap_size: {
-	ErlMessage *mp;
+	ErtsMessage *mp;
 	Uint total_heap_size;
 	Uint hsz = 3;
 
@@ -1418,8 +1349,6 @@ process_info_aux(Process *BIF_P,
 
 	total_heap_size += rp->mbuf_sz;
 
-	ERTS_SMP_MSGQ_MV_INQ2PRIVQ(rp);
-
 	for (mp = rp->msg.first; mp; mp = mp->next)
 	    if (mp->data.attached)
 		total_heap_size += erts_msg_attached_data_size(mp);
@@ -1441,7 +1370,7 @@ process_info_aux(Process *BIF_P,
 
     case am_memory: { /* Memory consumed in bytes */
 	Uint hsz = 3;
-	Uint size = erts_process_memory(rp);
+	Uint size = erts_process_memory(rp, 0);
 	(void) erts_bld_uint(NULL, &hsz, size);
 	hp = HAlloc(BIF_P, hsz);
 	res = erts_bld_uint(&hp, NULL, size);
@@ -1567,6 +1496,11 @@ process_info_aux(Process *BIF_P,
 	break;
     }
 
+    case am_off_heap_message_queue:
+	res = BIF_P->flags & F_OFF_HEAP_MSGQ ? am_true : am_false;
+	hp = HAlloc(BIF_P, 3);
+	break;
+
     default:
 	return THE_NON_VALUE; /* will produce badarg */
 
@@ -2728,6 +2662,10 @@ BIF_RETTYPE system_info_1(BIF_ALIST_1)
 	BIF_RET(am_true);
     }
 #endif
+    else if (BIF_ARG_1 == am_off_heap_message_queue) {
+	BIF_RET(erts_default_spo_flags & SPO_OFF_HEAP_MSGQ
+		? am_true : am_false);
+    }
     else if (ERTS_IS_ATOM_STR("compile_info",BIF_ARG_1)) {
 	Uint  sz;
 	Eterm res = NIL, tup, text;
@@ -2766,6 +2704,20 @@ BIF_RETTYPE system_info_1(BIF_ALIST_1)
     else if (ERTS_IS_ATOM_STR("eager_check_io",BIF_ARG_1)) {
 	BIF_RET(erts_eager_check_io ? am_true : am_false);
     }
+    else if (ERTS_IS_ATOM_STR("literal_test",BIF_ARG_1)) {
+#ifdef ERTS_HAVE_IS_IN_LITERAL_RANGE
+#ifdef ARCH_64
+	DECL_AM(range);
+	BIF_RET(AM_range);
+#else /* ARCH_32 */
+	DECL_AM(range_bitmask);
+	BIF_RET(AM_range_bitmask);
+#endif /* ARCH_32 */
+#else  /* ! ERTS_HAVE_IS_IN_LITERAL_RANGE */
+	DECL_AM(tag);
+	BIF_RET(AM_tag);
+#endif
+    }
 
     BIF_ERROR(BIF_P, BADARG);
 }
@@ -3851,9 +3803,7 @@ BIF_RETTYPE erts_debug_set_internal_state_2(BIF_ALIST_2)
 		BIF_RET(am_false);
 	    }
 	    else {
-		FLAGS(rp) |= F_FORCE_GC;
-		if (BIF_P != rp)
-		    erts_smp_proc_unlock(rp, ERTS_PROC_LOCK_MAIN);
+		ERTS_FORCE_GC(BIF_P);
 		BIF_RET(am_true);
 	    }
 	}
@@ -4323,12 +4273,15 @@ static void os_info_init(void)
     erts_free(ERTS_ALC_T_TMP, (void *) buf);
     hp = erts_alloc(ERTS_ALC_T_LITERAL, (3+4)*sizeof(Eterm));
     os_type_tuple = TUPLE2(hp, type, flav);
+    erts_set_literal_tag(&os_type_tuple, hp, 3);
+
     hp += 3;
     os_version(&major, &minor, &build);
     os_version_tuple = TUPLE3(hp,
 			      make_small(major),
 			      make_small(minor),
 			      make_small(build));
+    erts_set_literal_tag(&os_version_tuple, hp, 4);
 }
 
 void
diff --git a/erts/emulator/beam/erl_debug.c b/erts/emulator/beam/erl_debug.c
index fae38728e4..49b08c8536 100644
--- a/erts/emulator/beam/erl_debug.c
+++ b/erts/emulator/beam/erl_debug.c
@@ -312,6 +312,8 @@ void erts_check_for_holes(Process* p)
     p->last_htop = HEAP_TOP(p);
 
     for (hf = MBUF(p); hf != 0; hf = hf->next) {
+	if (hf == p->heap_hfrag)
+	    continue;
 	if (hf == p->last_mbuf) {
 	    break;
 	}
@@ -402,7 +404,7 @@ void verify_process(Process *p)
         erl_exit(1,"Wild pointer found in " name " of %T!\n",p->common.id); }
 
 
-    ErlMessage* mp = p->msg.first;
+    ErtsMessage* mp = p->msg.first;
 
     VERBOSE(DEBUG_MEMORY,("Verify process: %T...\n",p->common.id));
 
@@ -531,7 +533,7 @@ static void print_process_memory(Process *p)
                 PTR_SIZE, "PCB", dashes, dashes, dashes, dashes);
 
     if (p->msg.first != NULL) {
-        ErlMessage* mp;
+        ErtsMessage* mp;
         erts_printf("  Message Queue:\n");
         mp = p->msg.first;
         while (mp != NULL) {
diff --git a/erts/emulator/beam/erl_gc.c b/erts/emulator/beam/erl_gc.c
index 9a3f32c803..c8f40ee162 100644
--- a/erts/emulator/beam/erl_gc.c
+++ b/erts/emulator/beam/erl_gc.c
@@ -47,6 +47,17 @@
 #define ERTS_INACT_WR_PB_LEAVE_LIMIT 10
 #define ERTS_INACT_WR_PB_LEAVE_PERCENTAGE 10
 
+#if defined(DEBUG) || 0
+#define ERTS_GC_DEBUG
+#else
+#undef ERTS_GC_DEBUG
+#endif
+#ifdef ERTS_GC_DEBUG
+#  define ERTS_GC_ASSERT ASSERT
+#else
+#  define ERTS_GC_ASSERT(B) ((void) 1)
+#endif
+
 /*
  * Returns number of elements in an array.
  */
@@ -67,10 +78,10 @@
 #define ErtsGcQuickSanityCheck(P)					\
 do {									\
     ASSERT((P)->heap < (P)->hend);					\
-    ASSERT((P)->heap_sz == (P)->hend - (P)->heap);			\
+    ASSERT((p)->abandoned_heap || (P)->heap_sz == (P)->hend - (P)->heap); \
     ASSERT((P)->heap <= (P)->htop && (P)->htop <= (P)->hend);		\
     ASSERT((P)->heap <= (P)->stop && (P)->stop <= (P)->hend);		\
-    ASSERT((P)->heap <= (P)->high_water && (P)->high_water <= (P)->hend);\
+    ASSERT((p)->abandoned_heap || ((P)->heap <= (P)->high_water && (P)->high_water <= (P)->hend)); \
     OverRunCheck((P));							\
 } while (0)
 #else
@@ -98,17 +109,32 @@ typedef struct {
 
 static Uint setup_rootset(Process*, Eterm*, int, Rootset*);
 static void cleanup_rootset(Rootset *rootset);
-static Uint combined_message_size(Process* p);
 static void remove_message_buffers(Process* p);
-static int major_collection(Process* p, int need, Eterm* objv, int nobj, Uint *recl);
-static int minor_collection(Process* p, int need, Eterm* objv, int nobj, Uint *recl);
-static void do_minor(Process *p, Uint new_sz, Eterm* objv, int nobj);
-static Eterm* sweep_rootset(Rootset *rootset, Eterm* htop, char* src, Uint src_size);
-static Eterm* sweep_one_area(Eterm* n_hp, Eterm* n_htop, char* src, Uint src_size);
-static Eterm* sweep_one_heap(Eterm* heap_ptr, Eterm* heap_end, Eterm* htop,
-			     char* src, Uint src_size);
-static Eterm* collect_heap_frags(Process* p, Eterm* heap,
-				 Eterm* htop, Eterm* objv, int nobj);
+static Eterm *full_sweep_heaps(Process *p,
+			       int hibernate,
+			       Eterm *n_heap, Eterm* n_htop,
+			       char *oh, Uint oh_size,
+			       Eterm *objv, int nobj);
+static int garbage_collect(Process* p, ErlHeapFragment *live_hf_end,
+			   int need, Eterm* objv, int nobj);
+static int major_collection(Process* p, ErlHeapFragment *live_hf_end,
+			    int need, Eterm* objv, int nobj, Uint *recl);
+static int minor_collection(Process* p, ErlHeapFragment *live_hf_end,
+			    int need, Eterm* objv, int nobj, Uint *recl);
+static void do_minor(Process *p, ErlHeapFragment *live_hf_end,
+		     char *mature, Uint mature_size,
+		     Uint new_sz, Eterm* objv, int nobj);
+static Eterm *sweep_new_heap(Eterm *n_hp, Eterm *n_htop,
+			     char* old_heap, Uint old_heap_size);
+static Eterm *sweep_heaps(Eterm *n_hp, Eterm *n_htop,
+			  char* old_heap, Uint old_heap_size);
+static Eterm* sweep_literal_area(Eterm* n_hp, Eterm* n_htop,
+				 char* old_heap, Uint old_heap_size,
+				 char* src, Uint src_size);
+static Eterm* sweep_literals_to_old_heap(Eterm* heap_ptr, Eterm* heap_end, Eterm* htop,
+					 char* src, Uint src_size);
+static Eterm* collect_live_heap_frags(Process* p, ErlHeapFragment *live_hf_end,
+				      Eterm* heap, Eterm* htop, Eterm* objv, int nobj);
 static void adjust_after_fullsweep(Process *p, int need, Eterm *objv, int nobj);
 static void shrink_new_heap(Process *p, Uint new_sz, Eterm *objv, int nobj);
 static void grow_new_heap(Process *p, Uint new_sz, Eterm* objv, int nobj);
@@ -125,7 +151,6 @@ static void init_gc_info(ErtsGCInfo *gcip);
 #ifdef HARDDEBUG
 static void disallow_heap_frag_ref_in_heap(Process* p);
 static void disallow_heap_frag_ref_in_old_heap(Process* p);
-static void disallow_heap_frag_ref(Process* p, Eterm* n_htop, Eterm* objv, int nobj);
 #endif
 
 #if defined(ARCH_64)
@@ -332,10 +357,19 @@ erts_offset_off_heap(ErlOffHeap *ohp, Sint offs, Eterm* low, Eterm* high)
 #undef ptr_within
 
 Eterm
-erts_gc_after_bif_call(Process* p, Eterm result, Eterm* regs, Uint arity)
+erts_gc_after_bif_call_lhf(Process* p, ErlHeapFragment *live_hf_end,
+			   Eterm result, Eterm* regs, Uint arity)
 {
     int cost;
 
+    if (p->flags & F_HIBERNATE_SCHED) {
+	/*
+	 * We just hibernated. We do *not* want to mess
+	 * up the hibernation by an ordinary GC...
+	 */
+	return result;
+    }
+
     if (is_non_value(result)) {
 	if (p->freason == TRAP) {
 	  #if HIPE
@@ -343,21 +377,28 @@ erts_gc_after_bif_call(Process* p, Eterm result, Eterm* regs, Uint arity)
 		regs = ERTS_PROC_GET_SCHDATA(p)->x_reg_array;
 	    }
 	  #endif
-	    cost = erts_garbage_collect(p, 0, regs, p->arity);
+	    cost = garbage_collect(p, live_hf_end, 0, regs, p->arity);
 	} else {
-	    cost = erts_garbage_collect(p, 0, regs, arity);
+	    cost = garbage_collect(p, live_hf_end, 0, regs, arity);
 	}
     } else {
 	Eterm val[1];
 
 	val[0] = result;
-	cost = erts_garbage_collect(p, 0, val, 1);
+	cost = garbage_collect(p, live_hf_end, 0, val, 1);
 	result = val[0];
     }
     BUMP_REDS(p, cost);
     return result;
 }
 
+Eterm
+erts_gc_after_bif_call(Process* p, Eterm result, Eterm* regs, Uint arity)
+{
+    return erts_gc_after_bif_call_lhf(p, ERTS_INVALID_HFRAG_PTR,
+				      result, regs, arity);
+}
+
 static ERTS_INLINE void reset_active_writer(Process *p)
 {
     struct erl_off_heap_header* ptr;
@@ -371,6 +412,117 @@ static ERTS_INLINE void reset_active_writer(Process *p)
     }
 }
 
+#define ERTS_DELAY_GC_EXTRA_FREE 40
+
+static int
+delay_garbage_collection(Process *p, ErlHeapFragment *live_hf_end, int need)
+{
+    ErlHeapFragment *hfrag;
+    Eterm *orig_heap, *orig_hend, *orig_htop, *orig_stop;
+    Eterm *stop, *hend;
+    Uint hsz, ssz;
+
+    ERTS_HOLE_CHECK(p);
+
+    if (p->live_hf_end == ERTS_INVALID_HFRAG_PTR)
+	p->live_hf_end = live_hf_end;
+
+    if (need == 0)
+	return 1;
+
+    /*
+     * Satisfy need in a heap fragment...
+     */
+    ASSERT(need > 0);
+
+    orig_heap = p->heap;
+    orig_hend = p->hend;
+    orig_htop = p->htop;
+    orig_stop = p->stop;
+
+    ssz = orig_hend - orig_stop;
+    hsz = ssz + need + ERTS_DELAY_GC_EXTRA_FREE;
+
+    hfrag = new_message_buffer(hsz);
+    hfrag->next = p->mbuf;
+    p->mbuf = hfrag;
+    p->mbuf_sz += hsz;
+    p->heap = p->htop = &hfrag->mem[0];
+    p->hend = hend = &hfrag->mem[hsz];
+    p->stop = stop = hend - ssz;
+    sys_memcpy((void *) stop, (void *) orig_stop, ssz * sizeof(Eterm));
+
+    if (p->abandoned_heap) {
+	/* Active heap already in a fragment; adjust it... */
+	ErlHeapFragment *hfrag = ((ErlHeapFragment *)
+				  (((char *) orig_heap)
+				   - offsetof(ErlHeapFragment, mem)));
+	Uint unused = orig_hend - orig_htop;
+	ASSERT(hfrag->used_size == hfrag->alloc_size);
+	ASSERT(hfrag->used_size >= unused);
+	hfrag->used_size -= unused;
+	p->mbuf_sz -= unused;
+    }
+    else {
+	/* Do not leave a hole in the abandoned heap... */
+	if (orig_htop < orig_hend) {
+	    *orig_htop = make_pos_bignum_header(orig_hend-orig_htop-1);
+	    if (orig_htop + 1 < orig_hend) {
+		orig_hend[-1] = (Uint) (orig_htop - orig_heap);
+		p->flags |= F_ABANDONED_HEAP_USE;
+	    }
+	}
+	p->abandoned_heap = orig_heap;
+    }
+
+#ifdef CHECK_FOR_HOLES
+    p->last_htop = p->htop;
+    p->heap_hfrag = hfrag;
+#endif
+
+    /* Make sure that we do a proper GC as soon as possible... */
+    p->flags |= F_FORCE_GC;
+    return CONTEXT_REDS;
+}
+
+static ERTS_FORCE_INLINE Uint
+young_gen_usage(Process *p)
+{
+    Uint hsz;
+    Eterm *aheap;
+
+    hsz = p->mbuf_sz;
+    aheap = p->abandoned_heap;
+    if (!aheap)
+	hsz += p->htop - p->heap;
+    else {
+	/* used in orig heap */
+	if (p->flags & F_ABANDONED_HEAP_USE)
+	    hsz += aheap[p->heap_sz-1];
+	else
+	    hsz += p->heap_sz;
+	/* Remove unused part in latest fragment */
+	hsz -= p->hend - p->htop;
+    }
+    return hsz;
+}
+
+#define ERTS_GET_ORIG_HEAP(Proc, Heap, HTop)			\
+    do {							\
+	Eterm *aheap__ = (Proc)->abandoned_heap;		\
+	if (!aheap__) {						\
+	    (Heap) = (Proc)->heap;				\
+	    (HTop) = (Proc)->htop;				\
+	}							\
+	else {							\
+	    (Heap) = aheap__;					\
+	    if ((Proc)->flags & F_ABANDONED_HEAP_USE)		\
+		(HTop) = aheap__ + aheap__[(Proc)->heap_sz-1];	\
+	    else						\
+		(HTop) = aheap__ + (Proc)->heap_sz;		\
+	}							\
+    } while (0)
+
 /*
  * Garbage collect a process.
  *
@@ -379,8 +531,9 @@ static ERTS_INLINE void reset_active_writer(Process *p)
  * objv: Array of terms to add to rootset; that is to preserve.
  * nobj: Number of objects in objv.
  */
-int
-erts_garbage_collect(Process* p, int need, Eterm* objv, int nobj)
+static int
+garbage_collect(Process* p, ErlHeapFragment *live_hf_end,
+		int need, Eterm* objv, int nobj)
 {
     Uint reclaimed_now = 0;
     int done = 0;
@@ -390,10 +543,11 @@ erts_garbage_collect(Process* p, int need, Eterm* objv, int nobj)
     DTRACE_CHARBUF(pidbuf, DTRACE_TERM_BUF_SIZE);
 #endif
 
-    if (p->flags & F_DISABLE_GC) {
-	ASSERT(need == 0);
-	return 1;
-    }
+    if (p->flags & F_DISABLE_GC)
+	return delay_garbage_collection(p, live_hf_end, need);
+
+    if (p->live_hf_end != ERTS_INVALID_HFRAG_PTR)
+	live_hf_end = p->live_hf_end;
 
     esdp = erts_get_scheduler_data();
 
@@ -401,7 +555,7 @@ erts_garbage_collect(Process* p, int need, Eterm* objv, int nobj)
         trace_gc(p, am_gc_start);
     }
 
-    (void) erts_smp_atomic32_read_bor_nob(&p->state, ERTS_PSFLG_GC);
+    erts_smp_atomic32_read_bor_nob(&p->state, ERTS_PSFLG_GC);
     if (erts_system_monitor_long_gc != 0)
 	start_time = erts_get_monotonic_time(esdp);
 
@@ -426,11 +580,11 @@ erts_garbage_collect(Process* p, int need, Eterm* objv, int nobj)
     while (!done) {
 	if ((FLAGS(p) & F_NEED_FULLSWEEP) != 0) {
 	    DTRACE2(gc_major_start, pidbuf, need);
-	    done = major_collection(p, need, objv, nobj, &reclaimed_now);
+	    done = major_collection(p, live_hf_end, need, objv, nobj, &reclaimed_now);
 	    DTRACE2(gc_major_end, pidbuf, reclaimed_now);
 	} else {
 	    DTRACE2(gc_minor_start, pidbuf, need);
-	    done = minor_collection(p, need, objv, nobj, &reclaimed_now);
+	    done = minor_collection(p, live_hf_end, need, objv, nobj, &reclaimed_now);
 	    DTRACE2(gc_minor_end, pidbuf, reclaimed_now);
 	}
     }
@@ -472,6 +626,7 @@ erts_garbage_collect(Process* p, int need, Eterm* objv, int nobj)
     esdp->gc_info.reclaimed += reclaimed_now;
     
     FLAGS(p) &= ~F_FORCE_GC;
+    p->live_hf_end = ERTS_INVALID_HFRAG_PTR;
 
 #ifdef CHECK_FOR_HOLES
     /*
@@ -504,6 +659,12 @@ erts_garbage_collect(Process* p, int need, Eterm* objv, int nobj)
     }
 }
 
+int
+erts_garbage_collect(Process* p, int need, Eterm* objv, int nobj)
+{
+    return garbage_collect(p, ERTS_INVALID_HFRAG_PTR, need, objv, nobj);
+}
+
 /*
  * Place all living data on a the new heap; deallocate any old heap.
  * Meant to be used by hibernate/3.
@@ -514,9 +675,6 @@ erts_garbage_collect_hibernate(Process* p)
     Uint heap_size;
     Eterm* heap;
     Eterm* htop;
-    Rootset rootset;
-    char* src;
-    Uint src_size;
     Uint actual_size;
     char* area;
     Uint area_size;
@@ -530,55 +688,28 @@ erts_garbage_collect_hibernate(Process* p)
      */
     erts_smp_atomic32_read_bor_nob(&p->state, ERTS_PSFLG_GC);
     ErtsGcQuickSanityCheck(p);
-    ASSERT(p->mbuf_sz == 0);
-    ASSERT(p->mbuf == 0);
+    ASSERT(p->mbuf == NULL);
     ASSERT(p->stop == p->hend);	/* Stack must be empty. */
+    ASSERT(!p->abandoned_heap);
 
     /*
      * Do it.
      */
 
 
-    heap_size = p->heap_sz + (p->old_htop - p->old_heap);
+    heap_size = p->heap_sz + (p->old_htop - p->old_heap) + p->mbuf_sz;
     heap = (Eterm*) ERTS_HEAP_ALLOC(ERTS_ALC_T_TMP_HEAP,
 				    sizeof(Eterm)*heap_size);
     htop = heap;
 
-    (void) setup_rootset(p, p->arg_reg, p->arity, &rootset);
-#if HIPE
-    hipe_empty_nstack(p);
-#endif
-
-    src = (char *) p->heap;
-    src_size = (char *) p->htop - src;
-    htop = sweep_rootset(&rootset, htop, src, src_size);
-    htop = sweep_one_area(heap, htop, src, src_size);
-
-    if (p->old_heap) {
-	src = (char *) p->old_heap;
-	src_size = (char *) p->old_htop - src;
-	htop = sweep_rootset(&rootset, htop, src, src_size);
-	htop = sweep_one_area(heap, htop, src, src_size);
-    }
-
-    cleanup_rootset(&rootset);
-
-    if (MSO(p).first) {
-        sweep_off_heap(p, 1);
-    }
-
-    /*
-     *  Update all pointers.
-     */
-    ERTS_HEAP_FREE(ERTS_ALC_T_HEAP,
-		   (void*)HEAP_START(p),
-		   HEAP_SIZE(p) * sizeof(Eterm));
-    if (p->old_heap) {
-	ERTS_HEAP_FREE(ERTS_ALC_T_OLD_HEAP,
-		       (void*)p->old_heap,
-		       (p->old_hend - p->old_heap) * sizeof(Eterm));
-	p->old_heap = p->old_htop = p->old_hend = 0;
-    }
+    htop = full_sweep_heaps(p,
+			    1,
+			    heap,
+			    htop,
+			    (char *) p->old_heap,
+			    (char *) p->old_htop - (char *) p->old_heap,
+			    p->arg_reg,
+			    p->arity);
 
     p->heap = heap;
     p->high_water = htop;
@@ -593,6 +724,7 @@ erts_garbage_collect_hibernate(Process* p)
     }
 
     FLAGS(p) &= ~F_FORCE_GC;
+    p->live_hf_end = ERTS_INVALID_HFRAG_PTR;
 
     /*
      * Move the heap to its final destination.
@@ -612,6 +744,8 @@ erts_garbage_collect_hibernate(Process* p)
     sys_memcpy((void *) heap, (void *) p->heap, actual_size*sizeof(Eterm));
     ERTS_HEAP_FREE(ERTS_ALC_T_TMP_HEAP, p->heap, p->heap_sz*sizeof(Eterm));
 
+    remove_message_buffers(p);
+
     p->stop = p->hend = heap + heap_size;
 
     offs = heap - p->heap;
@@ -724,7 +858,7 @@ erts_garbage_collect_literals(Process* p, Eterm* literals,
                 if (IS_MOVED_BOXED(val)) {
 		    ASSERT(is_boxed(val));
                     *g_ptr++ = val;
-		} else if (in_area(ptr, area, area_size)) {
+		} else if (ErtsInArea(ptr, area, area_size)) {
                     MOVE_BOXED(ptr,val,old_htop,g_ptr++);
 		} else {
 		    g_ptr++;
@@ -735,7 +869,7 @@ erts_garbage_collect_literals(Process* p, Eterm* literals,
                 val = *ptr;
                 if (IS_MOVED_CONS(val)) { /* Moved */
                     *g_ptr++ = ptr[1];
-		} else if (in_area(ptr, area, area_size)) {
+		} else if (ErtsInArea(ptr, area, area_size)) {
                     MOVE_CONS(ptr,val,old_htop,g_ptr++);
                 } else {
 		    g_ptr++;
@@ -755,8 +889,10 @@ erts_garbage_collect_literals(Process* p, Eterm* literals,
      * Now we'll have to go through all heaps updating all other references.
      */
 
-    old_htop = sweep_one_heap(p->heap, p->htop, old_htop, area, area_size);
-    old_htop = sweep_one_area(p->old_heap, old_htop, area, area_size);
+    old_htop = sweep_literals_to_old_heap(p->heap, p->htop, old_htop, area, area_size);
+    old_htop = sweep_literal_area(p->old_heap, old_htop,
+				  (char *) p->old_heap, sizeof(Eterm)*old_heap_size,
+				  area, area_size);
     ASSERT(p->old_htop <= old_htop && old_htop <= p->old_hend);
     p->old_htop = old_htop;
 
@@ -815,15 +951,18 @@ erts_garbage_collect_literals(Process* p, Eterm* literals,
 }
 
 static int
-minor_collection(Process* p, int need, Eterm* objv, int nobj, Uint *recl)
+minor_collection(Process* p, ErlHeapFragment *live_hf_end,
+		 int need, Eterm* objv, int nobj, Uint *recl)
 {
-    Uint mature = HIGH_WATER(p) - HEAP_START(p);
+    Eterm *mature = p->abandoned_heap ? p->abandoned_heap : p->heap;
+    Uint mature_size = p->high_water - mature;
+    Uint size_before = young_gen_usage(p);
 
     /*
      * Allocate an old heap if we don't have one and if we'll need one.
      */
 
-    if (OLD_HEAP(p) == NULL && mature != 0) {
+    if (OLD_HEAP(p) == NULL && mature_size != 0) {
         Eterm* n_old;
 
         /* Note: We choose a larger heap size than strictly needed,
@@ -831,7 +970,7 @@ minor_collection(Process* p, int need, Eterm* objv, int nobj, Uint *recl)
          * This improved Estone by more than 1200 estones on my computer
          * (Ultra Sparc 10).
          */
-        Uint new_sz = erts_next_heap_size(HEAP_TOP(p) - HEAP_START(p), 1);
+        Uint new_sz = erts_next_heap_size(size_before, 1);
 
         /* Create new, empty old_heap */
         n_old = (Eterm *) ERTS_HEAP_ALLOC(ERTS_ALC_T_OLD_HEAP,
@@ -847,40 +986,24 @@ minor_collection(Process* p, int need, Eterm* objv, int nobj, Uint *recl)
      */
 
     if (OLD_HEAP(p) &&
-	    ((mature <= OLD_HEND(p) - OLD_HTOP(p)) &&
-	    ((BIN_OLD_VHEAP_SZ(p) > BIN_OLD_VHEAP(p))) ) ) {
-	ErlMessage *msgp;
-	Uint size_after;
-	Uint need_after;
-	const Uint stack_size = STACK_SZ_ON_HEAP(p);
-	const Uint size_before = MBUF_SIZE(p) + (HEAP_TOP(p) - HEAP_START(p));
-	Uint new_sz = HEAP_SIZE(p) + MBUF_SIZE(p) + combined_message_size(p);
+	((mature_size <= OLD_HEND(p) - OLD_HTOP(p)) &&
+	 ((BIN_OLD_VHEAP_SZ(p) > BIN_OLD_VHEAP(p))) ) ) {
+	Uint stack_size, size_after, need_after, new_sz;
+
+	stack_size = p->hend - p->stop;
+	new_sz = stack_size + size_before;
         new_sz = next_heap_size(p, new_sz, 0);
 
-        do_minor(p, new_sz, objv, nobj);
+        do_minor(p, live_hf_end, (char *) mature, mature_size*sizeof(Eterm),
+		 new_sz, objv, nobj);
 
         size_after = HEAP_TOP(p) - HEAP_START(p);
         *recl += (size_before - size_after);
 
-        /*
-	 * Copy newly received message onto the end of the new heap.
-	 */
-        ErtsGcQuickSanityCheck(p);
-        for (msgp = p->msg.first; msgp; msgp = msgp->next) {
-            if (msgp->data.attached) {
-                ErtsHeapFactory factory;
-                erts_factory_proc_prealloc_init(&factory, p,
-                                                erts_msg_attached_data_size(msgp));
-                erts_move_msg_attached_data_to_heap(&factory, msgp);
-                erts_factory_close(&factory);
-                ErtsGcQuickSanityCheck(p);
-            }
-        }
 	ErtsGcQuickSanityCheck(p);
 
         GEN_GCS(p)++;
         need_after = ((HEAP_TOP(p) - HEAP_START(p))
-                      + erts_used_frag_sz(MBUF(p))
                       + need
                       + stack_size);
 	
@@ -929,10 +1052,13 @@ minor_collection(Process* p, int need, Eterm* objv, int nobj, Uint *recl)
             ASSERT(MBUF(p) == NULL);
             return 1;
 	}
+
+        grow_new_heap(p, next_heap_size(p, need_after, 0), objv, nobj);
+	return 1;
     }
 
     /*
-     * Still not enough room after minor collection. Must force a major collection.
+     * Not enough room for a minor collection. Must force a major collection.
      */
     FLAGS(p) |= F_NEED_FULLSWEEP;
     return 0;
@@ -989,7 +1115,9 @@ static ERTS_INLINE void offset_nstack(Process* p, Sint offs,
 #endif /* HIPE */
 
 static void
-do_minor(Process *p, Uint new_sz, Eterm* objv, int nobj)
+do_minor(Process *p, ErlHeapFragment *live_hf_end,
+	 char *mature, Uint mature_size,
+	 Uint new_sz, Eterm* objv, int nobj)
 {
     Rootset rootset;            /* Rootset for GC (stack, dictionary, etc). */
     Roots* roots;
@@ -998,17 +1126,21 @@ do_minor(Process *p, Uint new_sz, Eterm* objv, int nobj)
     Eterm* ptr;
     Eterm val;
     Eterm gval;
-    char* heap = (char *) HEAP_START(p);
-    Uint heap_size = (char *) HEAP_TOP(p) - heap;
-    Uint mature_size = (char *) HIGH_WATER(p) - heap;
     Eterm* old_htop = OLD_HTOP(p);
     Eterm* n_heap;
+    char* oh = (char *) OLD_HEAP(p);
+    Uint oh_size = (char *) OLD_HTOP(p) - oh;
 
     n_htop = n_heap = (Eterm*) ERTS_HEAP_ALLOC(ERTS_ALC_T_HEAP,
 					       sizeof(Eterm)*new_sz);
 
-    if (MBUF(p) != NULL) {
-	n_htop = collect_heap_frags(p, n_heap, n_htop, objv, nobj);
+    if (live_hf_end != ERTS_INVALID_HFRAG_PTR) {
+	/*
+	 * Move heap frags that we know are completely live
+	 * directly into the new young heap generation.
+	 */
+	n_htop = collect_live_heap_frags(p, live_hf_end, n_heap, n_htop,
+					 objv, nobj);
     }
 
     n = setup_rootset(p, objv, nobj, &rootset);
@@ -1031,9 +1163,9 @@ do_minor(Process *p, Uint new_sz, Eterm* objv, int nobj)
                 if (IS_MOVED_BOXED(val)) {
 		    ASSERT(is_boxed(val));
                     *g_ptr++ = val;
-                } else if (in_area(ptr, heap, mature_size)) {
+                } else if (ErtsInArea(ptr, mature, mature_size)) {
                     MOVE_BOXED(ptr,val,old_htop,g_ptr++);
-                } else if (in_area(ptr, heap, heap_size)) {
+                } else if (ErtsInYoungGen(gval, ptr, oh, oh_size)) {
                     MOVE_BOXED(ptr,val,n_htop,g_ptr++);
                 } else {
 		    g_ptr++;
@@ -1046,9 +1178,9 @@ do_minor(Process *p, Uint new_sz, Eterm* objv, int nobj)
                 val = *ptr;
                 if (IS_MOVED_CONS(val)) { /* Moved */
                     *g_ptr++ = ptr[1];
-                } else if (in_area(ptr, heap, mature_size)) {
+                } else if (ErtsInArea(ptr, mature, mature_size)) {
                     MOVE_CONS(ptr,val,old_htop,g_ptr++);
-                } else if (in_area(ptr, heap, heap_size)) {
+                } else if (ErtsInYoungGen(gval, ptr, oh, oh_size)) {
                     MOVE_CONS(ptr,val,n_htop,g_ptr++);
                 } else {
 		    g_ptr++;
@@ -1073,7 +1205,7 @@ do_minor(Process *p, Uint new_sz, Eterm* objv, int nobj)
      */
 
     if (mature_size == 0) {
-	n_htop = sweep_one_area(n_heap, n_htop, heap, heap_size);
+	n_htop = sweep_new_heap(n_heap, n_htop, oh, oh_size);
     } else {
 	Eterm* n_hp = n_heap;
 	Eterm* ptr;
@@ -1090,9 +1222,9 @@ do_minor(Process *p, Uint new_sz, Eterm* objv, int nobj)
 		if (IS_MOVED_BOXED(val)) {
 		    ASSERT(is_boxed(val));
 		    *n_hp++ = val;
-		} else if (in_area(ptr, heap, mature_size)) {
+		} else if (ErtsInArea(ptr, mature, mature_size)) {
 		    MOVE_BOXED(ptr,val,old_htop,n_hp++);
-		} else if (in_area(ptr, heap, heap_size)) {
+		} else if (ErtsInYoungGen(gval, ptr, oh, oh_size)) {
 		    MOVE_BOXED(ptr,val,n_htop,n_hp++);
 		} else {
 		    n_hp++;
@@ -1104,9 +1236,9 @@ do_minor(Process *p, Uint new_sz, Eterm* objv, int nobj)
 		val = *ptr;
 		if (IS_MOVED_CONS(val)) {
 		    *n_hp++ = ptr[1];
-		} else if (in_area(ptr, heap, mature_size)) {
+		} else if (ErtsInArea(ptr, mature, mature_size)) {
 		    MOVE_CONS(ptr,val,old_htop,n_hp++);
-		} else if (in_area(ptr, heap, heap_size)) {
+		} else if (ErtsInYoungGen(gval, ptr, oh, oh_size)) {
 		    MOVE_CONS(ptr,val,n_htop,n_hp++);
 		} else {
 		    n_hp++;
@@ -1126,10 +1258,10 @@ do_minor(Process *p, Uint new_sz, Eterm* objv, int nobj)
 			if (IS_MOVED_BOXED(val)) {
 			    *origptr = val;
 			    mb->base = binary_bytes(val);
-			} else if (in_area(ptr, heap, mature_size)) {
+			} else if (ErtsInArea(ptr, mature, mature_size)) {
 			    MOVE_BOXED(ptr,val,old_htop,origptr);
 			    mb->base = binary_bytes(mb->orig);
-			} else if (in_area(ptr, heap, heap_size)) {
+			} else if (ErtsInYoungGen(*origptr, ptr, oh, oh_size)) {
 			    MOVE_BOXED(ptr,val,n_htop,origptr);
 			    mb->base = binary_bytes(mb->orig);
 			}
@@ -1150,9 +1282,8 @@ do_minor(Process *p, Uint new_sz, Eterm* objv, int nobj)
      * may point to the old (soon to be deleted) new_heap.
      */
 
-    if (OLD_HTOP(p) < old_htop) {
-	old_htop = sweep_one_area(OLD_HTOP(p), old_htop, heap, heap_size);
-    }
+    if (OLD_HTOP(p) < old_htop)
+	old_htop = sweep_new_heap(OLD_HTOP(p), old_htop, oh, oh_size);
     OLD_HTOP(p) = old_htop;
     HIGH_WATER(p) = n_htop;
 
@@ -1184,8 +1315,12 @@ do_minor(Process *p, Uint new_sz, Eterm* objv, int nobj)
 #endif
 
     ERTS_HEAP_FREE(ERTS_ALC_T_HEAP,
-		   (void*)HEAP_START(p),
+		   (p->abandoned_heap
+		    ? p->abandoned_heap
+		    : HEAP_START(p)),
 		   HEAP_SIZE(p) * sizeof(Eterm));
+    p->abandoned_heap = NULL;
+    p->flags &= ~F_ABANDONED_HEAP_USE;
     HEAP_START(p) = n_heap;
     HEAP_TOP(p) = n_htop;
     HEAP_SIZE(p) = new_sz;
@@ -1202,30 +1337,26 @@ do_minor(Process *p, Uint new_sz, Eterm* objv, int nobj)
  */
 
 static int
-major_collection(Process* p, int need, Eterm* objv, int nobj, Uint *recl)
+major_collection(Process* p, ErlHeapFragment *live_hf_end,
+		 int need, Eterm* objv, int nobj, Uint *recl)
 {
-    Rootset rootset;
-    Roots* roots;
-    const Uint size_before = ((HEAP_TOP(p) - HEAP_START(p))
-                              + (OLD_HTOP(p) - OLD_HEAP(p))
-                              + MBUF_SIZE(p));
+    Uint size_before, stack_size;
     Eterm* n_heap;
     Eterm* n_htop;
-    char* src = (char *) HEAP_START(p);
-    Uint src_size = (char *) HEAP_TOP(p) - src;
     char* oh = (char *) OLD_HEAP(p);
     Uint oh_size = (char *) OLD_HTOP(p) - oh;
-    Uint n;
-    Uint new_sz;
+    Uint new_sz, stk_sz;
 
     /*
      * Do a fullsweep GC. First figure out the size of the heap
      * to receive all live data.
      */
 
-    new_sz = (HEAP_SIZE(p) + MBUF_SIZE(p)
-              + combined_message_size(p)
-              + (OLD_HTOP(p) - OLD_HEAP(p)));
+    size_before = young_gen_usage(p);
+    size_before += p->old_htop - p->old_heap;
+    stack_size = p->hend - p->stop;
+
+    new_sz = stack_size + size_before;
     new_sz = next_heap_size(p, new_sz, 0);
 
     /*
@@ -1239,13 +1370,71 @@ major_collection(Process* p, int need, Eterm* objv, int nobj, Uint *recl)
     n_htop = n_heap = (Eterm *) ERTS_HEAP_ALLOC(ERTS_ALC_T_HEAP,
 						sizeof(Eterm)*new_sz);
 
-    /*
-     * Get rid of heap fragments.
-     */
+    if (live_hf_end != ERTS_INVALID_HFRAG_PTR) {
+	/*
+	 * Move heap frags that we know are completely live
+	 * directly into the heap.
+	 */
+	n_htop = collect_live_heap_frags(p, live_hf_end, n_heap, n_htop,
+					 objv, nobj);
+    }
 
-    if (MBUF(p) != NULL) {
-	n_htop = collect_heap_frags(p, n_heap, n_htop, objv, nobj);
+    n_htop = full_sweep_heaps(p, 0, n_heap, n_htop, oh, oh_size, objv, nobj);
+
+    /* Move the stack to the end of the heap */
+    stk_sz = HEAP_END(p) - p->stop;
+    sys_memcpy(n_heap + new_sz - stk_sz, p->stop, stk_sz * sizeof(Eterm));
+    p->stop = n_heap + new_sz - stk_sz;
+
+#ifdef USE_VM_PROBES
+    if (HEAP_SIZE(p) != new_sz && DTRACE_ENABLED(process_heap_grow)) {
+        DTRACE_CHARBUF(pidbuf, DTRACE_TERM_BUF_SIZE);
+
+        dtrace_proc_str(p, pidbuf);
+        DTRACE3(process_heap_grow, pidbuf, HEAP_SIZE(p), new_sz);
     }
+#endif
+
+    ERTS_HEAP_FREE(ERTS_ALC_T_HEAP,
+		   (p->abandoned_heap
+		    ? p->abandoned_heap
+		    : HEAP_START(p)),
+		   (HEAP_END(p) - HEAP_START(p)) * sizeof(Eterm));
+    p->abandoned_heap = NULL;
+    p->flags &= ~F_ABANDONED_HEAP_USE;
+    HEAP_START(p) = n_heap;
+    HEAP_TOP(p) = n_htop;
+    HEAP_SIZE(p) = new_sz;
+    HEAP_END(p) = n_heap + new_sz;
+    GEN_GCS(p) = 0;
+
+    HIGH_WATER(p) = HEAP_TOP(p);
+
+    ErtsGcQuickSanityCheck(p);
+
+    *recl += size_before - (HEAP_TOP(p) - HEAP_START(p));
+
+    adjust_after_fullsweep(p, need, objv, nobj);
+
+#ifdef HARDDEBUG
+    disallow_heap_frag_ref_in_heap(p);
+#endif
+    remove_message_buffers(p);
+
+    ErtsGcQuickSanityCheck(p);
+    return 1;			/* We are done. */
+}
+
+static Eterm *
+full_sweep_heaps(Process *p,
+		 int hibernate,
+		 Eterm *n_heap, Eterm* n_htop,
+		 char *oh, Uint oh_size,
+		 Eterm *objv, int nobj)
+{
+    Rootset rootset;
+    Roots *roots;
+    Uint n;
 
     /*
      * Copy all top-level terms directly referenced by the rootset to
@@ -1253,7 +1442,14 @@ major_collection(Process* p, int need, Eterm* objv, int nobj, Uint *recl)
      */
 
     n = setup_rootset(p, objv, nobj, &rootset);
-    n_htop = fullsweep_nstack(p, n_htop);
+
+#ifdef HIPE
+    if (hibernate)
+	hipe_empty_nstack(p);
+    else
+	n_htop = fullsweep_nstack(p, n_htop);
+#endif
+
     roots = rootset.roots;
     while (n--) {
 	Eterm* g_ptr = roots->v;
@@ -1273,7 +1469,7 @@ major_collection(Process* p, int need, Eterm* objv, int nobj, Uint *recl)
 		if (IS_MOVED_BOXED(val)) {
 		    ASSERT(is_boxed(val));
 		    *g_ptr++ = val;
-		} else if (in_area(ptr, src, src_size) || in_area(ptr, oh, oh_size)) {
+		} else if (!erts_is_literal(gval, ptr)) {
 		    MOVE_BOXED(ptr,val,n_htop,g_ptr++);
 		} else {
 		    g_ptr++;
@@ -1286,7 +1482,7 @@ major_collection(Process* p, int need, Eterm* objv, int nobj, Uint *recl)
 		val = *ptr;
 		if (IS_MOVED_CONS(val)) {
 		    *g_ptr++ = ptr[1];
-		} else if (in_area(ptr, src, src_size) || in_area(ptr, oh, oh_size)) {
+		} else if (!erts_is_literal(gval, ptr)) {
 		    MOVE_CONS(ptr,val,n_htop,g_ptr++);
 		} else {
 		    g_ptr++;
@@ -1311,74 +1507,7 @@ major_collection(Process* p, int need, Eterm* objv, int nobj, Uint *recl)
      * until all is copied.
      */
 
-    if (oh_size == 0) {
-	n_htop = sweep_one_area(n_heap, n_htop, src, src_size);
-    } else {
-	Eterm* n_hp = n_heap;
-
-	while (n_hp != n_htop) {
-	    Eterm* ptr;
-	    Eterm val;
-	    Eterm gval = *n_hp;
-
-	    switch (primary_tag(gval)) {
-	    case TAG_PRIMARY_BOXED: {
-		ptr = boxed_val(gval);
-		val = *ptr;
-		if (IS_MOVED_BOXED(val)) {
-		    ASSERT(is_boxed(val));
-		    *n_hp++ = val;
-		} else if (in_area(ptr, src, src_size) || in_area(ptr, oh, oh_size)) {
-		    MOVE_BOXED(ptr,val,n_htop,n_hp++);
-		} else {
-		    n_hp++;
-		}
-		break;
-	    }
-	    case TAG_PRIMARY_LIST: {
-		ptr = list_val(gval);
-		val = *ptr;
-		if (IS_MOVED_CONS(val)) {
-		    *n_hp++ = ptr[1];
-		} else if (in_area(ptr, src, src_size) || in_area(ptr, oh, oh_size)) {
-		    MOVE_CONS(ptr,val,n_htop,n_hp++);
-		} else {
-		    n_hp++;
-		}
-		break;
-	    }
-	    case TAG_PRIMARY_HEADER: {
-		if (!header_is_thing(gval))
-		    n_hp++;
-		else {
-		    if (header_is_bin_matchstate(gval)) {
-			ErlBinMatchState *ms = (ErlBinMatchState*) n_hp;
-			ErlBinMatchBuffer *mb = &(ms->mb);
-			Eterm* origptr;	
-			origptr = &(mb->orig);
-			ptr = boxed_val(*origptr);
-			val = *ptr;
-			if (IS_MOVED_BOXED(val)) {
-			    *origptr = val;
-			    mb->base = binary_bytes(*origptr);
-			} else if (in_area(ptr, src, src_size) ||
-				   in_area(ptr, oh, oh_size)) {
-			    MOVE_BOXED(ptr,val,n_htop,origptr); 
-			    mb->base = binary_bytes(*origptr);
-			    ptr = boxed_val(*origptr);
-			    val = *ptr;
-			}
-		    }
-		    n_hp += (thing_arityval(gval)+1);
-		}
-		break;
-	    }
-	    default:
-		n_hp++;
-		break;
-	    }
-	}
-    }
+    n_htop = sweep_heaps(n_heap, n_htop, oh, oh_size);
 
     if (MSO(p).first) {
 	sweep_off_heap(p, 1);
@@ -1391,62 +1520,7 @@ major_collection(Process* p, int need, Eterm* objv, int nobj, Uint *recl)
 	OLD_HEAP(p) = OLD_HTOP(p) = OLD_HEND(p) = NULL;
     }
 
-    /* Move the stack to the end of the heap */
-    n = HEAP_END(p) - p->stop;
-    sys_memcpy(n_heap + new_sz - n, p->stop, n * sizeof(Eterm));
-    p->stop = n_heap + new_sz - n;
-
-#ifdef USE_VM_PROBES
-    if (HEAP_SIZE(p) != new_sz && DTRACE_ENABLED(process_heap_grow)) {
-        DTRACE_CHARBUF(pidbuf, DTRACE_TERM_BUF_SIZE);
-
-        dtrace_proc_str(p, pidbuf);
-        DTRACE3(process_heap_grow, pidbuf, HEAP_SIZE(p), new_sz);
-    }
-#endif
-
-    ERTS_HEAP_FREE(ERTS_ALC_T_HEAP,
-		   (void *) HEAP_START(p),
-		   (HEAP_END(p) - HEAP_START(p)) * sizeof(Eterm));
-    HEAP_START(p) = n_heap;
-    HEAP_TOP(p) = n_htop;
-    HEAP_SIZE(p) = new_sz;
-    HEAP_END(p) = n_heap + new_sz;
-    GEN_GCS(p) = 0;
-
-    HIGH_WATER(p) = HEAP_TOP(p);
-
-    ErtsGcQuickSanityCheck(p);
-
-    *recl += size_before - (HEAP_TOP(p) - HEAP_START(p));
-
-    {
-	ErlMessage *msgp;
-
-	/*
-	 * Copy newly received message onto the end of the new heap.
-	 */
-        for (msgp = p->msg.first; msgp; msgp = msgp->next) {
-	    if (msgp->data.attached) {
-                ErtsHeapFactory factory;
-                erts_factory_proc_prealloc_init(&factory, p,
-                                                erts_msg_attached_data_size(msgp));
-		erts_move_msg_attached_data_to_heap(&factory, msgp);
-                erts_factory_close(&factory);
-		ErtsGcQuickSanityCheck(p);
-	    }
-	}
-    }
-
-    adjust_after_fullsweep(p, need, objv, nobj);
-
-#ifdef HARDDEBUG
-    disallow_heap_frag_ref_in_heap(p);
-#endif
-    remove_message_buffers(p);
-
-    ErtsGcQuickSanityCheck(p);
-    return 1;			/* We are done. */
+    return n_htop;
 }
 
 static void
@@ -1485,23 +1559,6 @@ adjust_after_fullsweep(Process *p, int need, Eterm *objv, int nobj)
 }
 
 /*
- * Return the size of all message buffers that are NOT linked in the
- * mbuf list.
- */
-static Uint
-combined_message_size(Process* p)
-{
-    Uint sz;
-    ErlMessage *msgp;
-
-    for (sz = 0, msgp = p->msg.first; msgp; msgp = msgp->next) {
-	if (msgp->data.attached)
-	    sz += erts_msg_attached_data_size(msgp);
-    }
-    return sz;
-}
-
-/*
  * Remove all message buffers.
  */
 static void
@@ -1511,6 +1568,10 @@ remove_message_buffers(Process* p)
 	free_message_buffer(MBUF(p));
 	MBUF(p) = NULL;
     }    
+    if (p->msg_frag) {
+	erts_cleanup_messages(p->msg_frag);
+	p->msg_frag = NULL;
+    }
     MBUF_SIZE(p) = 0;    
 }
 #ifdef HARDDEBUG
@@ -1522,64 +1583,6 @@ remove_message_buffers(Process* p)
  * For performance reasons, we use _unchecked_list_val(), _unchecked_boxed_val(),
  * and so on to avoid a function call.
  */
- 
-static void
-disallow_heap_frag_ref(Process* p, Eterm* n_htop, Eterm* objv, int nobj)
-{
-    ErlHeapFragment* mbuf;
-    ErlHeapFragment* qb;
-    Eterm gval;
-    Eterm* ptr;
-    Eterm val;
-
-    ASSERT(p->htop != NULL);
-    mbuf = MBUF(p);
-
-    while (nobj--) {
-	gval = *objv;
-	
-	switch (primary_tag(gval)) {
-
-	case TAG_PRIMARY_BOXED: {
-	    ptr = _unchecked_boxed_val(gval);
-	    val = *ptr;
-	    if (IS_MOVED_BOXED(val)) {
-		ASSERT(is_boxed(val));
-		objv++;
-	    } else {
- 		for (qb = mbuf; qb != NULL; qb = qb->next) {
-		    if (in_area(ptr, qb->mem, qb->alloc_size*sizeof(Eterm))) {
-			abort();
-		    }
-		}
-		objv++;
-	    }
-	    break;
-	}
-
-	case TAG_PRIMARY_LIST: {
-	    ptr = _unchecked_list_val(gval);
-	    val = *ptr;
-	    if (IS_MOVED_CONS(val)) {
-		objv++;
-	    } else {
-		for (qb = mbuf; qb != NULL; qb = qb->next) {
-		    if (in_area(ptr, qb->mem, qb->alloc_size*sizeof(Eterm))) {
-			abort();
-		    }
-		}
-		objv++;
-	    }
-	    break;
-	}
-
-	default: {
-	    objv++;
-	    break;
-	}
-	}
-    }
-}
 
 static void
 disallow_heap_frag_ref_in_heap(Process* p)
@@ -1607,9 +1610,9 @@ disallow_heap_frag_ref_in_heap(Process* p)
 	switch (primary_tag(val)) {
 	case TAG_PRIMARY_BOXED:
 	    ptr = _unchecked_boxed_val(val);
-	    if (!in_area(ptr, heap, heap_size)) {
+	    if (!ErtsInArea(ptr, heap, heap_size)) {
 		for (qb = MBUF(p); qb != NULL; qb = qb->next) {
-		    if (in_area(ptr, qb->mem, qb->alloc_size*sizeof(Eterm))) {
+		    if (ErtsInArea(ptr, qb->mem, qb->alloc_size*sizeof(Eterm))) {
 			abort();
 		    }
 		}
@@ -1617,9 +1620,9 @@ disallow_heap_frag_ref_in_heap(Process* p)
 	    break;
 	case TAG_PRIMARY_LIST:
 	    ptr = _unchecked_list_val(val);
-	    if (!in_area(ptr, heap, heap_size)) {
+	    if (!ErtsInArea(ptr, heap, heap_size)) {
 		for (qb = MBUF(p); qb != NULL; qb = qb->next) {
-		    if (in_area(ptr, qb->mem, qb->alloc_size*sizeof(Eterm))) {
+		    if (ErtsInArea(ptr, qb->mem, qb->alloc_size*sizeof(Eterm))) {
 			abort();
 		    }
 		}
@@ -1662,12 +1665,12 @@ disallow_heap_frag_ref_in_old_heap(Process* p)
 	switch (primary_tag(val)) {
 	case TAG_PRIMARY_BOXED:
 	    ptr = (Eterm *) val;
-	    if (!in_area(ptr, old_heap, old_heap_size)) {
-		if (in_area(ptr, new_heap, new_heap_size)) {
+	    if (!ErtsInArea(ptr, old_heap, old_heap_size)) {
+		if (ErtsInArea(ptr, new_heap, new_heap_size)) {
 		    abort();
 		}
 		for (qb = MBUF(p); qb != NULL; qb = qb->next) {
-		    if (in_area(ptr, qb->mem, qb->alloc_size*sizeof(Eterm))) {
+		    if (ErtsInArea(ptr, qb->mem, qb->alloc_size*sizeof(Eterm))) {
 			abort();
 		    }
 		}
@@ -1675,12 +1678,12 @@ disallow_heap_frag_ref_in_old_heap(Process* p)
 	    break;
 	case TAG_PRIMARY_LIST:
 	    ptr = (Eterm *) val;
-	    if (!in_area(ptr, old_heap, old_heap_size)) {
-		if (in_area(ptr, new_heap, new_heap_size)) {
+	    if (!ErtsInArea(ptr, old_heap, old_heap_size)) {
+		if (ErtsInArea(ptr, new_heap, new_heap_size)) {
 		    abort();
 		}
 		for (qb = MBUF(p); qb != NULL; qb = qb->next) {
-		    if (in_area(ptr, qb->mem, qb->alloc_size*sizeof(Eterm))) {
+		    if (ErtsInArea(ptr, qb->mem, qb->alloc_size*sizeof(Eterm))) {
 			abort();
 		    }
 		}
@@ -1689,7 +1692,7 @@ disallow_heap_frag_ref_in_old_heap(Process* p)
 	case TAG_PRIMARY_HEADER:
 	    if (header_is_thing(val)) {
 		hp += _unchecked_thing_arityval(val);
-		if (!in_area(hp, old_heap, old_heap_size+1)) {
+		if (!ErtsInArea(hp, old_heap, old_heap_size+1)) {
 		    abort();
 		}
 	    }
@@ -1699,66 +1702,30 @@ disallow_heap_frag_ref_in_old_heap(Process* p)
 }
 #endif
 
-static Eterm*
-sweep_rootset(Rootset* rootset, Eterm* htop, char* src, Uint src_size)
+typedef enum {
+    ErtsSweepNewHeap,
+    ErtsSweepHeaps,
+    ErtsSweepLiteralArea
+} ErtsSweepType;
+
+static ERTS_FORCE_INLINE Eterm *
+sweep(Eterm *n_hp, Eterm *n_htop,
+      ErtsSweepType type,
+      char *oh, Uint ohsz,
+      char *src, Uint src_size)
 {
-    Roots* roots = rootset->roots;
-    Uint n = rootset->num_roots;
     Eterm* ptr;
-    Eterm gval;
     Eterm val;
+    Eterm gval;
 
-    while (n--) {
-        Eterm* g_ptr = roots->v;
-        Uint g_sz = roots->sz;
-
-	roots++;
-        while (g_sz--) {
-            gval = *g_ptr;
-
-            switch (primary_tag(gval)) {
-	    case TAG_PRIMARY_BOXED: {
-		ptr = boxed_val(gval);
-                val = *ptr;
-                if (IS_MOVED_BOXED(val)) {
-		    ASSERT(is_boxed(val));
-                    *g_ptr++ = val;
-                } else if (in_area(ptr, src, src_size)) {
-                    MOVE_BOXED(ptr,val,htop,g_ptr++);
-                } else {
-		    g_ptr++;
-		}
-                break;
-	    }
-	    case TAG_PRIMARY_LIST: {
-                ptr = list_val(gval);
-                val = *ptr;
-                if (IS_MOVED_CONS(val)) {
-                    *g_ptr++ = ptr[1];
-                } else if (in_area(ptr, src, src_size)) {
-                    MOVE_CONS(ptr,val,htop,g_ptr++);
-                } else {
-		    g_ptr++;
-		}
-		break;
-	    }
-
-	    default:
-                g_ptr++;
-		break;
-            }
-        }
-    }
-    return htop;
-}
-
+#undef ERTS_IS_IN_SWEEP_AREA
 
-static Eterm*
-sweep_one_area(Eterm* n_hp, Eterm* n_htop, char* src, Uint src_size)
-{
-    Eterm* ptr;
-    Eterm val;
-    Eterm gval;
+#define ERTS_IS_IN_SWEEP_AREA(TPtr, Ptr)				\
+    (type == ErtsSweepHeaps						\
+     ? !erts_is_literal((TPtr), (Ptr))					\
+     : (type == ErtsSweepNewHeap					\
+	? ErtsInYoungGen((TPtr), (Ptr), oh, ohsz)			\
+	: ErtsInArea((Ptr), src, src_size)))
 
     while (n_hp != n_htop) {
 	ASSERT(n_hp < n_htop);
@@ -1770,7 +1737,7 @@ sweep_one_area(Eterm* n_hp, Eterm* n_htop, char* src, Uint src_size)
 	    if (IS_MOVED_BOXED(val)) {
 		ASSERT(is_boxed(val));
 		*n_hp++ = val;
-	    } else if (in_area(ptr, src, src_size)) {
+	    } else if (ERTS_IS_IN_SWEEP_AREA(gval, ptr)) {
 		MOVE_BOXED(ptr,val,n_htop,n_hp++);
 	    } else {
 		n_hp++;
@@ -1782,7 +1749,7 @@ sweep_one_area(Eterm* n_hp, Eterm* n_htop, char* src, Uint src_size)
 	    val = *ptr;
 	    if (IS_MOVED_CONS(val)) {
 		*n_hp++ = ptr[1];
-	    } else if (in_area(ptr, src, src_size)) {
+	    } else if (ERTS_IS_IN_SWEEP_AREA(gval, ptr)) {
 		MOVE_CONS(ptr,val,n_htop,n_hp++);
 	    } else {
 		n_hp++;
@@ -1803,7 +1770,7 @@ sweep_one_area(Eterm* n_hp, Eterm* n_htop, char* src, Uint src_size)
 		    if (IS_MOVED_BOXED(val)) {
 			*origptr = val;
 			mb->base = binary_bytes(*origptr);
-		    } else if (in_area(ptr, src, src_size)) {
+		    } else if (ERTS_IS_IN_SWEEP_AREA(*origptr, ptr)) {
 			MOVE_BOXED(ptr,val,n_htop,origptr); 
 			mb->base = binary_bytes(*origptr);
 		    }
@@ -1818,10 +1785,41 @@ sweep_one_area(Eterm* n_hp, Eterm* n_htop, char* src, Uint src_size)
 	}
     }
     return n_htop;
+#undef ERTS_IS_IN_SWEEP_AREA
+}
+
+static Eterm *
+sweep_new_heap(Eterm *n_hp, Eterm *n_htop, char* old_heap, Uint old_heap_size)
+{
+    return sweep(n_hp, n_htop,
+		 ErtsSweepNewHeap,
+		 old_heap, old_heap_size,
+		 NULL, 0);
+}
+
+static Eterm *
+sweep_heaps(Eterm *n_hp, Eterm *n_htop, char* old_heap, Uint old_heap_size)
+{
+    return sweep(n_hp, n_htop,
+		 ErtsSweepHeaps,
+		 old_heap, old_heap_size,
+		 NULL, 0);
+}
+
+static Eterm *
+sweep_literal_area(Eterm *n_hp, Eterm *n_htop,
+		   char* old_heap, Uint old_heap_size,
+		   char* src, Uint src_size)
+{
+    return sweep(n_hp, n_htop,
+		 ErtsSweepLiteralArea,
+		 old_heap, old_heap_size,
+		 src, src_size);
 }
 
 static Eterm*
-sweep_one_heap(Eterm* heap_ptr, Eterm* heap_end, Eterm* htop, char* src, Uint src_size)
+sweep_literals_to_old_heap(Eterm* heap_ptr, Eterm* heap_end, Eterm* htop,
+			   char* src, Uint src_size)
 {
     while (heap_ptr < heap_end) {
 	Eterm* ptr;
@@ -1835,7 +1833,7 @@ sweep_one_heap(Eterm* heap_ptr, Eterm* heap_end, Eterm* htop, char* src, Uint sr
 	    if (IS_MOVED_BOXED(val)) {
 		ASSERT(is_boxed(val));
 		*heap_ptr++ = val;
-	    } else if (in_area(ptr, src, src_size)) {
+	    } else if (ErtsInArea(ptr, src, src_size)) {
 		MOVE_BOXED(ptr,val,htop,heap_ptr++);
 	    } else {
 		heap_ptr++;
@@ -1847,7 +1845,7 @@ sweep_one_heap(Eterm* heap_ptr, Eterm* heap_end, Eterm* htop, char* src, Uint sr
 	    val = *ptr;
 	    if (IS_MOVED_CONS(val)) {
 		*heap_ptr++ = ptr[1];
-	    } else if (in_area(ptr, src, src_size)) {
+	    } else if (ErtsInArea(ptr, src, src_size)) {
 		MOVE_CONS(ptr,val,htop,heap_ptr++);
 	    } else {
 		heap_ptr++;
@@ -1868,7 +1866,7 @@ sweep_one_heap(Eterm* heap_ptr, Eterm* heap_end, Eterm* htop, char* src, Uint sr
 		    if (IS_MOVED_BOXED(val)) {
 			*origptr = val;
 			mb->base = binary_bytes(*origptr);
-		    } else if (in_area(ptr, src, src_size)) {
+		    } else if (ErtsInArea(ptr, src, src_size)) {
 			MOVE_BOXED(ptr,val,htop,origptr);
 			mb->base = binary_bytes(*origptr);
 		    }
@@ -1919,32 +1917,21 @@ move_one_area(Eterm* n_htop, char* src, Uint src_size)
  */
 
 static Eterm*
-collect_heap_frags(Process* p, Eterm* n_hstart, Eterm* n_htop,
-		   Eterm* objv, int nobj)
+collect_live_heap_frags(Process* p, ErlHeapFragment *live_hf_end,
+			Eterm* n_hstart, Eterm* n_htop,
+			Eterm* objv, int nobj)
 {
     ErlHeapFragment* qb;
     char* frag_begin;
     Uint frag_size;
 
     /*
-     * We don't allow references to a heap fragments from the stack, heap,
-     * or process dictionary.
-     */
-#ifdef HARDDEBUG
-    disallow_heap_frag_ref(p, n_htop, p->stop, STACK_START(p) - p->stop);
-    if (p->dictionary != NULL) {
-	disallow_heap_frag_ref(p, n_htop, p->dictionary->data, p->dictionary->used);
-    }
-    disallow_heap_frag_ref_in_heap(p);
-#endif
-
-    /*
      * Move the heap fragments to the new heap. Note that no GC is done on
      * the heap fragments. Any garbage will thus be moved as well and survive
      * until next GC.  
      */ 
     qb = MBUF(p);
-    while (qb != NULL) {
+    while (qb != live_hf_end) {
         ASSERT(!qb->off_heap.first);  /* process fragments use the MSO(p) list */
 	frag_size = qb->used_size * sizeof(Eterm);
 	if (frag_size != 0) {
@@ -1959,9 +1946,7 @@ collect_heap_frags(Process* p, Eterm* n_hstart, Eterm* n_htop,
 static Uint
 setup_rootset(Process *p, Eterm *objv, int nobj, Rootset *rootset)
 {
-    Uint avail;
     Roots* roots;
-    ErlMessage* mp;
     Uint n;
 
     n = 0;
@@ -1984,7 +1969,7 @@ setup_rootset(Process *p, Eterm *objv, int nobj, Rootset *rootset)
     }
 
     ASSERT((is_nil(p->seq_trace_token) ||
-	    is_tuple(follow_moved(p->seq_trace_token)) ||
+	    is_tuple(follow_moved(p->seq_trace_token, (Eterm) 0)) ||
 	    is_atom(p->seq_trace_token)));
     if (is_not_immed(p->seq_trace_token)) {
 	roots[n].v = &p->seq_trace_token;
@@ -2002,7 +1987,7 @@ setup_rootset(Process *p, Eterm *objv, int nobj, Rootset *rootset)
 	   is_internal_pid(ERTS_TRACER_PROC(p)) ||
 	   is_internal_port(ERTS_TRACER_PROC(p)));
 
-    ASSERT(is_pid(follow_moved(p->group_leader)));
+    ASSERT(is_pid(follow_moved(p->group_leader, (Eterm) 0)));
     if (is_not_immed(p->group_leader)) {
 	roots[n].v  = &p->group_leader;
 	roots[n].sz = 1;
@@ -2039,31 +2024,48 @@ setup_rootset(Process *p, Eterm *objv, int nobj, Rootset *rootset)
 
     ASSERT(n <= rootset->size);
 
-    mp = p->msg.first;
-    avail = rootset->size - n;
-    while (mp != NULL) {
-	if (avail == 0) {
-	    Uint new_size = 2*rootset->size;
-	    if (roots == rootset->def) {
-		roots = erts_alloc(ERTS_ALC_T_ROOTSET,
-				   new_size*sizeof(Roots));
-		sys_memcpy(roots, rootset->def, sizeof(rootset->def));
-	    } else {
-		roots = erts_realloc(ERTS_ALC_T_ROOTSET,
-				     (void *) roots,
-				     new_size*sizeof(Roots));
-	    }
+    switch (p->flags & (F_OFF_HEAP_MSGQ|F_OFF_HEAP_MSGQ_CHNG)) {
+    case F_OFF_HEAP_MSGQ|F_OFF_HEAP_MSGQ_CHNG:
+	(void) erts_move_messages_off_heap(p);
+    case F_OFF_HEAP_MSGQ:
+	break;
+    case F_OFF_HEAP_MSGQ_CHNG:
+    case 0: {
+	/*
+	 * Off heap message queue disabled, i.e. we may
+	 * have references from the message queue to the
+	 * heap...
+	 */
+	ErtsMessage *mp;
+
+	/* Ensure large enough rootset... */
+	if (n + p->msg.len > rootset->size) {
+	    Uint new_size = n + p->msg.len;
+	    ERTS_GC_ASSERT(roots == rootset->def);
+	    roots = erts_alloc(ERTS_ALC_T_ROOTSET,
+			       new_size*sizeof(Roots));
+	    sys_memcpy(roots, rootset->def, n*sizeof(Roots));
 	    rootset->size = new_size;
-	    avail = new_size - n;
 	}
-	if (mp->data.attached == NULL) {
-	    roots[n].v = mp->m;
-	    roots[n].sz = 2;
-	    n++;
-	    avail--;
+
+	for (mp = p->msg.first; mp; mp = mp->next) {
+
+	    if (!mp->data.attached) {
+		/*
+		 * Message may refer data on heap;
+		 * add it to rootset...
+		 */
+		roots[n].v = mp->m;
+		roots[n].sz = ERL_MESSAGE_REF_ARRAY_SZ;
+		n++;
+	    }
 	}
-        mp = mp->next;
+	break;
+    }
     }
+
+    ASSERT(rootset->size >= n);
+
     rootset->roots = roots;
     rootset->num_roots = n;
     return n;
@@ -2303,11 +2305,11 @@ sweep_off_heap(Process *p, int fullsweep)
      */
     while (ptr) {
 	if (IS_MOVED_BOXED(ptr->thing_word)) {
-	    ASSERT(!in_area(ptr, oheap, oheap_sz));
+	    ASSERT(!ErtsInArea(ptr, oheap, oheap_sz));
 	    *prev = ptr = (struct erl_off_heap_header*) boxed_val(ptr->thing_word);
 	    ASSERT(!IS_MOVED_BOXED(ptr->thing_word));
 	    if (ptr->thing_word == HEADER_PROC_BIN) {
-		int to_new_heap = !in_area(ptr, oheap, oheap_sz);
+		int to_new_heap = !ErtsInArea(ptr, oheap, oheap_sz);
 		ASSERT(to_new_heap == !seen_mature || (!to_new_heap && (seen_mature=1)));
 		if (to_new_heap) {
 		    bin_vheap += ptr->size / sizeof(Eterm);
@@ -2321,7 +2323,7 @@ sweep_off_heap(Process *p, int fullsweep)
 		ptr = ptr->next;
 	    }
 	}
-	else if (!in_area(ptr, oheap, oheap_sz)) {
+	else if (!ErtsInArea(ptr, oheap, oheap_sz)) {
 	    /* garbage */
 	    switch (thing_subtag(ptr->thing_word)) {
 	    case REFC_BINARY_SUBTAG:
@@ -2353,7 +2355,7 @@ sweep_off_heap(Process *p, int fullsweep)
      * generational collection - keep objects in list.
      */
     while (ptr) {
-	ASSERT(in_area(ptr, oheap, oheap_sz));
+	ASSERT(ErtsInArea(ptr, oheap, oheap_sz));
 	ASSERT(!IS_MOVED_BOXED(ptr->thing_word));       
 	if (ptr->thing_word == HEADER_PROC_BIN) {
 	    BIN_OLD_VHEAP(p) += ptr->size / sizeof(Eterm); /* for binary gc (words)*/
@@ -2442,7 +2444,7 @@ offset_heap(Eterm* hp, Uint sz, Sint offs, char* area, Uint area_size)
 	switch (primary_tag(val)) {
 	  case TAG_PRIMARY_LIST:
 	  case TAG_PRIMARY_BOXED:
-	      if (in_area(ptr_val(val), area, area_size)) {
+	      if (ErtsInArea(ptr_val(val), area, area_size)) {
 		  *hp = offset_ptr(val, offs);
 	      }
 	      hp++;
@@ -2464,7 +2466,7 @@ offset_heap(Eterm* hp, Uint sz, Sint offs, char* area, Uint area_size)
 		  {
 		      struct erl_off_heap_header* oh = (struct erl_off_heap_header*) hp;
 
-		      if (in_area(oh->next, area, area_size)) {
+		      if (ErtsInArea(oh->next, area, area_size)) {
 			  Eterm** uptr = (Eterm **) (void *) &oh->next;
 			  *uptr += offs; /* Patch the mso chain */
 		      }
@@ -2474,7 +2476,7 @@ offset_heap(Eterm* hp, Uint sz, Sint offs, char* area, Uint area_size)
 		{	
 		  ErlBinMatchState *ms = (ErlBinMatchState*) hp;
 		  ErlBinMatchBuffer *mb = &(ms->mb);
-		  if (in_area(ptr_val(mb->orig), area, area_size)) {
+		  if (ErtsInArea(ptr_val(mb->orig), area, area_size)) {
 		      mb->orig = offset_ptr(mb->orig, offs);
 		      mb->base = binary_bytes(mb->orig);
 		  }
@@ -2504,7 +2506,7 @@ offset_heap_ptr(Eterm* hp, Uint sz, Sint offs, char* area, Uint area_size)
 	switch (primary_tag(val)) {
 	case TAG_PRIMARY_LIST:
 	case TAG_PRIMARY_BOXED:
-	    if (in_area(ptr_val(val), area, area_size)) {
+	    if (ErtsInArea(ptr_val(val), area, area_size)) {
 		*hp = offset_ptr(val, offs);
 	    }
 	    hp++;
@@ -2519,7 +2521,7 @@ offset_heap_ptr(Eterm* hp, Uint sz, Sint offs, char* area, Uint area_size)
 static void
 offset_off_heap(Process* p, Sint offs, char* area, Uint area_size)
 {
-    if (MSO(p).first && in_area((Eterm *)MSO(p).first, area, area_size)) {
+    if (MSO(p).first && ErtsInArea((Eterm *)MSO(p).first, area, area_size)) {
         Eterm** uptr = (Eterm**) (void *) &MSO(p).first;
         *uptr += offs;
     }
@@ -2531,7 +2533,7 @@ offset_off_heap(Process* p, Sint offs, char* area, Uint area_size)
 static void
 offset_mqueue(Process *p, Sint offs, char* area, Uint area_size)
 {
-    ErlMessage* mp = p->msg.first;
+    ErtsMessage* mp = p->msg.first;
 
     while (mp != NULL) {
         Eterm mesg = ERL_MESSAGE_TERM(mp);
@@ -2539,19 +2541,19 @@ offset_mqueue(Process *p, Sint offs, char* area, Uint area_size)
 	    switch (primary_tag(mesg)) {
 	    case TAG_PRIMARY_LIST:
 	    case TAG_PRIMARY_BOXED:
-		if (in_area(ptr_val(mesg), area, area_size)) {
+		if (ErtsInArea(ptr_val(mesg), area, area_size)) {
 		    ERL_MESSAGE_TERM(mp) = offset_ptr(mesg, offs);
 		}
 		break;
 	    }
 	}
 	mesg = ERL_MESSAGE_TOKEN(mp);
-	if (is_boxed(mesg) && in_area(ptr_val(mesg), area, area_size)) {
+	if (is_boxed(mesg) && ErtsInArea(ptr_val(mesg), area, area_size)) {
 	    ERL_MESSAGE_TOKEN(mp) = offset_ptr(mesg, offs);
         }
 #ifdef USE_VM_PROBES
 	mesg = ERL_MESSAGE_DT_UTAG(mp);
-	if (is_boxed(mesg) && in_area(ptr_val(mesg), area, area_size)) {
+	if (is_boxed(mesg) && ErtsInArea(ptr_val(mesg), area, area_size)) {
 	    ERL_MESSAGE_DT_UTAG(mp) = offset_ptr(mesg, offs);
         }
 #endif	
@@ -2618,7 +2620,7 @@ reply_gc_info(void *vgcirp)
     Eterm **hpp;
     Uint sz, *szp;
     ErlOffHeap *ohp = NULL;
-    ErlHeapFragment *bp = NULL;
+    ErtsMessage *mp = NULL;
 
     ASSERT(esdp);
 
@@ -2644,12 +2646,13 @@ reply_gc_info(void *vgcirp)
 	if (hpp)
 	  break;
 	
-	hp = erts_alloc_message_heap(sz, &bp, &ohp, rp, &rp_locks);
+	mp = erts_alloc_message_heap(rp, &rp_locks, sz, &hp, &ohp);
+
 	szp = NULL;
 	hpp = &hp;
     }
 
-    erts_queue_message(rp, &rp_locks, bp, msg, NIL);
+    erts_queue_message(rp, &rp_locks, mp, msg, NIL);
 
     if (gcirp->req_sched == esdp->no)
 	rp_locks &= ~ERTS_PROC_LOCK_MAIN;
@@ -2701,36 +2704,49 @@ erts_gc_info_request(Process *c_p)
 static int
 within2(Eterm *ptr, Process *p, Eterm *real_htop)
 {
-    ErlHeapFragment* bp = MBUF(p);
-    ErlMessage* mp = p->msg.first;
-    Eterm *htop = real_htop ? real_htop : HEAP_TOP(p);
+    ErlHeapFragment* bp;
+    ErtsMessage* mp;
+    Eterm *htop, *heap;
+
+    if (p->abandoned_heap)
+	ERTS_GET_ORIG_HEAP(p, heap, htop);
+    else {
+	heap = p->heap;
+	htop = real_htop ? real_htop : HEAP_TOP(p);
+    }
 
     if (OLD_HEAP(p) && (OLD_HEAP(p) <= ptr && ptr < OLD_HEND(p))) {
         return 1;
     }
-    if (HEAP_START(p) <= ptr && ptr < htop) {
+    if (heap <= ptr && ptr < htop) {
         return 1;
     }
-    while (bp != NULL) {
-        if (bp->mem <= ptr && ptr < bp->mem + bp->used_size) {
-            return 1;
-        }
-        bp = bp->next;
-    }
+
+    mp = p->msg_frag;
+    bp = p->mbuf;
+
+    if (bp)
+	goto search_heap_frags;
+
     while (mp) {
-	if (mp->data.attached) {
-	    ErlHeapFragment *hfp;
-	    if (is_value(ERL_MESSAGE_TERM(mp)))
-		hfp = mp->data.heap_frag;
-	    else if (is_not_nil(ERL_MESSAGE_TOKEN(mp)))
-		hfp = erts_dist_ext_trailer(mp->data.dist_ext);
-	    else
-		hfp = NULL;
-	    if (hfp && hfp->mem <= ptr && ptr < hfp->mem + hfp->used_size)
+
+	if (mp->data.attached == ERTS_MSG_COMBINED_HFRAG)
+	    bp = &mp->hfrag;
+	else
+	    bp = mp->data.heap_frag;
+
+	mp = mp->next;
+
+    search_heap_frags:
+
+	while (bp) {
+	    if (bp->mem <= ptr && ptr < bp->mem + bp->used_size) {
 		return 1;
+	    }
+	    bp = bp->next;
 	}
-        mp = mp->next;
     }
+
     return 0;
 }
 
@@ -2752,11 +2768,11 @@ do {							\
 		 __FILE__, __LINE__, #EXP);		\
 } while (0)
 
+
 #ifdef ERTS_OFFHEAP_DEBUG_CHK_CIRCULAR_LIST
 #  define ERTS_OFFHEAP_VISITED_BIT ((Eterm) 1 << 31)
 #endif
 
-
 void
 erts_check_off_heap2(Process *p, Eterm *htop)
 {
@@ -2785,7 +2801,7 @@ erts_check_off_heap2(Process *p, Eterm *htop)
 	}
 	ERTS_CHK_OFFHEAP_ASSERT(refc >= 1);
 #ifdef ERTS_OFFHEAP_DEBUG_CHK_CIRCULAR_LIST
-	ERTS_CHK_OFFHEAP_ASSERT(!(u.hdr->thing_word & ERTS_EXTERNAL_VISITED_BIT));
+	ERTS_CHK_OFFHEAP_ASSERT(!(u.hdr->thing_word & ERTS_OFFHEAP_VISITED_BIT));
 	u.hdr->thing_word |= ERTS_OFFHEAP_VISITED_BIT;
 #endif
 	if (old) {
@@ -2798,7 +2814,7 @@ erts_check_off_heap2(Process *p, Eterm *htop)
 	}
     }
 
-#ifdef ERTS_OFFHEAP_DEBUG_CHK_CIRCULAR_EXTERNAL_LIST
+#ifdef ERTS_OFFHEAP_DEBUG_CHK_CIRCULAR_LIST
     for (u.hdr = MSO(p).first; u.hdr; u.hdr = u.hdr->next)
 	u.hdr->thing_word &= ~ERTS_OFFHEAP_VISITED_BIT;
 #endif
diff --git a/erts/emulator/beam/erl_gc.h b/erts/emulator/beam/erl_gc.h
index ecd1bf4d22..a496c5f008 100644
--- a/erts/emulator/beam/erl_gc.h
+++ b/erts/emulator/beam/erl_gc.h
@@ -69,17 +69,18 @@ do {                                                                    \
     while (nelts--) *HTOP++ = *PTR++;                                   \
 } while(0)
 
-#define in_area(ptr,start,nbytes) \
- ((UWord)((char*)(ptr) - (char*)(start)) < (nbytes))
-
 #if defined(DEBUG) || defined(ERTS_OFFHEAP_DEBUG)
 int within(Eterm *ptr, Process *p);
 #endif
 
-ERTS_GLB_INLINE Eterm follow_moved(Eterm term);
+#define ErtsInYoungGen(TPtr, Ptr, OldHeap, OldHeapSz)			\
+    (!erts_is_literal((TPtr), (Ptr))					\
+     & !ErtsInArea((Ptr), (OldHeap), (OldHeapSz)))
+
+ERTS_GLB_INLINE Eterm follow_moved(Eterm term, Eterm xptr_tag);
 
 #if ERTS_GLB_INLINE_INCL_FUNC_DEF
-ERTS_GLB_INLINE Eterm follow_moved(Eterm term)
+ERTS_GLB_INLINE Eterm follow_moved(Eterm term, Eterm xptr_tag)
 {
     Eterm* ptr;
     switch (primary_tag(term)) {
@@ -87,17 +88,18 @@ ERTS_GLB_INLINE Eterm follow_moved(Eterm term)
 	break;
     case TAG_PRIMARY_BOXED:
 	ptr = boxed_val(term);
-	if (IS_MOVED_BOXED(*ptr)) term = *ptr;
+	if (IS_MOVED_BOXED(*ptr)) term = (*ptr) | xptr_tag;
 	break;
     case TAG_PRIMARY_LIST:
 	ptr = list_val(term);
-	if (IS_MOVED_CONS(ptr[0])) term = ptr[1];
+	if (IS_MOVED_CONS(ptr[0])) term = (ptr[1]) | xptr_tag;
 	break;
     default:
 	ASSERT(!"strange tag in follow_moved");
     }
     return term;
 }
+
 #endif
 
 #endif /* ERL_GC_C__ || HIPE_GC_C__ */
@@ -106,6 +108,23 @@ ERTS_GLB_INLINE Eterm follow_moved(Eterm term)
  * Global exported
  */
 
+#define ERTS_IS_GC_DESIRED_INTERNAL(Proc, HTop, STop)			\
+    ((((STop) - (HTop) < (Proc)->mbuf_sz))				\
+     | ((Proc)->off_heap.overhead > (Proc)->bin_vheap_sz)		\
+     | !!((Proc)->flags & F_FORCE_GC))
+
+#define ERTS_IS_GC_DESIRED(Proc)					\
+    ERTS_IS_GC_DESIRED_INTERNAL((Proc), (Proc)->htop, (Proc)->stop)
+
+#define ERTS_FORCE_GC_INTERNAL(Proc, FCalls)				\
+    do {								\
+	(Proc)->flags |= F_FORCE_GC;					\
+	ERTS_VBUMP_ALL_REDS_INTERNAL((Proc), (FCalls));			\
+    } while (0)
+
+#define ERTS_FORCE_GC(Proc)						\
+    ERTS_FORCE_GC_INTERNAL((Proc), (Proc)->fcalls)
+
 extern Uint erts_test_long_gc_sleep;
 
 typedef struct {
@@ -117,6 +136,8 @@ void erts_gc_info(ErtsGCInfo *gcip);
 void erts_init_gc(void);
 int erts_garbage_collect(struct process*, int, Eterm*, int);
 void erts_garbage_collect_hibernate(struct process* p);
+Eterm erts_gc_after_bif_call_lhf(struct process* p, ErlHeapFragment *live_hf_end,
+				 Eterm result, Eterm* regs, Uint arity);
 Eterm erts_gc_after_bif_call(struct process* p, Eterm result, Eterm* regs, Uint arity);
 void erts_garbage_collect_literals(struct process* p, Eterm* literals,
 				   Uint lit_size,
diff --git a/erts/emulator/beam/erl_hl_timer.c b/erts/emulator/beam/erl_hl_timer.c
index 51a0d68247..6853278828 100644
--- a/erts/emulator/beam/erl_hl_timer.c
+++ b/erts/emulator/beam/erl_hl_timer.c
@@ -1245,7 +1245,9 @@ hlt_bif_timer_timeout(ErtsHLTimer *tmr, Uint32 roflgs)
 	 * the middle of tree destruction).
 	 */
 	if (!ERTS_PROC_IS_EXITING(proc)) {
-	    erts_queue_message(proc, &proc_locks, tmr->btm.bp,
+	    ErtsMessage *mp = erts_alloc_message(0, NULL);
+	    mp->data.heap_frag = tmr->btm.bp;
+	    erts_queue_message(proc, &proc_locks, mp,
 			       tmr->btm.message, NIL);
 	    erts_smp_proc_unlock(proc, ERTS_PROC_LOCKS_MSG_SEND);
 	    queued_message = 1;
@@ -1926,36 +1928,31 @@ access_sched_local_btm(Process *c_p, Eterm pid,
 
     if (proc) {
 	Uint hsz;
-	ErlOffHeap *ohp;
-	ErlHeapFragment* bp;
+	ErtsMessage *mp;
 	Eterm *hp, msg, ref, result;
+	ErlOffHeap *ohp;
+	Uint32 *refn;
 #ifdef ERTS_HLT_DEBUG
 	Eterm *hp_end;
 #endif
 
-	hsz = 3; /* 2-tuple */
-	if (!async)
-	    hsz += REF_THING_SIZE;
+	hsz = REF_THING_SIZE;
+	if (async) {
+	    refn = trefn; /* timer ref */
+	    hsz += 4; /* 3-tuple */
+	}
 	else {
-	    if (is_non_value(tref) || proc != c_p)
-		hsz += REF_THING_SIZE;
-	    hsz += 1; /* upgrade to 3-tuple */
+	    refn = rrefn; /* request ref */
+	    hsz += 3; /* 2-tuple */
 	}
+
+	ERTS_HLT_ASSERT(refn);
+
 	if (time_left > (Sint64) MAX_SMALL)
 	    hsz += ERTS_SINT64_HEAP_SIZE(time_left);
 
-	if (proc == c_p) {
-	    bp = NULL;
-	    ohp = NULL;
-	    hp = HAlloc(c_p, hsz);
-	}
-	else {
-	    hp = erts_alloc_message_heap(hsz,
-					 &bp,
-					 &ohp,
-					 proc,
-					 &proc_locks);
-	}
+	mp = erts_alloc_message_heap(proc, &proc_locks,
+				     hsz, &hp, &ohp);
 
 #ifdef ERTS_HLT_DEBUG
 	hp_end = hp + hsz;
@@ -1968,35 +1965,22 @@ access_sched_local_btm(Process *c_p, Eterm pid,
 	else
 	    result = erts_sint64_to_big(time_left, &hp);
 
-	if (!async) {
-	    write_ref_thing(hp,
-			    rrefn[0],
-			    rrefn[1],
-			    rrefn[2]);
-	    ref = make_internal_ref(hp);
-	    hp += REF_THING_SIZE;
-	    msg = TUPLE2(hp, ref, result);
+	write_ref_thing(hp,
+			refn[0],
+			refn[1],
+			refn[2]);
+	ref = make_internal_ref(hp);
+	hp += REF_THING_SIZE;
 
-	    ERTS_HLT_ASSERT(hp + 3 == hp_end);
-	}
-	else {
-	    Eterm tag = cancel ? am_cancel_timer : am_read_timer;
-	    if (is_value(tref) && proc == c_p)
-		ref = tref;
-	    else {
-		write_ref_thing(hp,
-				trefn[0],
-				trefn[1],
-				trefn[2]);
-		ref = make_internal_ref(hp);
-		hp += REF_THING_SIZE;
-	    }
-	    msg = TUPLE3(hp, tag, ref, result);
+	msg = (async
+	       ? TUPLE3(hp, (cancel
+			     ? am_cancel_timer
+			     : am_read_timer), ref, result)
+	       : TUPLE2(hp, ref, result));
 
-	    ERTS_HLT_ASSERT(hp + 4 == hp_end);
+	ERTS_HLT_ASSERT(hp + (async ? 4 : 3) == hp_end);
 
-	}
-	erts_queue_message(proc, &proc_locks, bp, msg, NIL);
+	erts_queue_message(proc, &proc_locks, mp, msg, NIL);
 
 	if (c_p)
 	    proc_locks &= ~ERTS_PROC_LOCK_MAIN;
@@ -2093,16 +2077,19 @@ try_access_sched_remote_btm(ErtsSchedulerData *esdp,
 	}
     }
     else {
+	ErtsMessage *mp;
 	Eterm tag, res, msg;
 	Uint hsz;
 	Eterm *hp;
 	ErtsProcLocks proc_locks = ERTS_PROC_LOCK_MAIN;
+	ErlOffHeap *ohp;
 
 	hsz = 4;
 	if (time_left > (Sint64) MAX_SMALL)
 	    hsz += ERTS_SINT64_HEAP_SIZE(time_left);
 
-	hp = HAlloc(c_p, hsz);
+	mp = erts_alloc_message_heap(c_p, &proc_locks,
+				     hsz, &hp, &ohp);
 	if (cancel)
 	    tag = am_cancel_timer;
 	else
@@ -2117,7 +2104,7 @@ try_access_sched_remote_btm(ErtsSchedulerData *esdp,
 
 	msg = TUPLE3(hp, tag, tref, res);
 
-	erts_queue_message(c_p, &proc_locks, NULL, msg, NIL);
+	erts_queue_message(c_p, &proc_locks, mp, msg, NIL);
 
 	proc_locks &= ~ERTS_PROC_LOCK_MAIN;
 	if (proc_locks)
diff --git a/erts/emulator/beam/erl_init.c b/erts/emulator/beam/erl_init.c
index 5c209a4af2..f396a0a156 100644
--- a/erts/emulator/beam/erl_init.c
+++ b/erts/emulator/beam/erl_init.c
@@ -431,7 +431,7 @@ erl_first_process_otp(char* modname, void* code, unsigned size, int argc, char**
     hp += 2;
     args = CONS(hp, env, args);
 
-    so.flags = SPO_SYSTEM_PROC;
+    so.flags = erts_default_spo_flags|SPO_SYSTEM_PROC;
     res = erl_create_process(&parent, start_mod, am_start, args, &so);
     erts_smp_proc_unlock(&parent, ERTS_PROC_LOCK_MAIN);
     erts_cleanup_empty_process(&parent);
@@ -630,6 +630,7 @@ void erts_usage(void)
 
     erts_fprintf(stderr, "-W<i|w|e>      set error logger warnings mapping,\n");
     erts_fprintf(stderr, "               see error_logger documentation for details\n");
+    erts_fprintf(stderr, "-xohmq  bool   set default off_heap_message_queue flag for processes\n");
     erts_fprintf(stderr, "-zdbbl size    set the distribution buffer busy limit in kilobytes\n");
     erts_fprintf(stderr, "               valid range is [1-%d]\n", INT_MAX/1024);
     erts_fprintf(stderr, "-zdntgc time   set delayed node table gc in seconds\n");
@@ -2015,6 +2016,26 @@ erl_start(int argc, char **argv)
 	    }
 	    break;
 
+	case 'x': {
+	    char *sub_param = argv[i]+2;
+	    if (has_prefix("ohmq", sub_param)) {
+		arg = get_arg(sub_param+4, argv[i+1], &i);
+		if (sys_strcmp(arg, "true") == 0)
+		    erts_default_spo_flags |= SPO_OFF_HEAP_MSGQ;
+		else if (sys_strcmp(arg, "false") == 0)
+		    erts_default_spo_flags &= ~SPO_OFF_HEAP_MSGQ;
+		else {
+		    erts_fprintf(stderr,
+				 "Invalid off_heap_message_queue flag: %s\n", arg);
+		    erts_usage();
+		}
+	    } else {
+		erts_fprintf(stderr, "bad -x option %s\n", argv[i]);
+		erts_usage();
+	    }
+	    break;
+        }
+
 	case 'z': {
 	    char *sub_param = argv[i]+2;
 
@@ -2068,7 +2089,8 @@ erl_start(int argc, char **argv)
 				 "Invalid ets busy wait threshold: %s\n", arg);
 		    erts_usage();
 		}
-	    } else {
+	    }
+	    else {
 		erts_fprintf(stderr, "bad -z option %s\n", argv[i]);
 		erts_usage();
 	    }
diff --git a/erts/emulator/beam/erl_message.c b/erts/emulator/beam/erl_message.c
index ef52823287..79739501a8 100644
--- a/erts/emulator/beam/erl_message.c
+++ b/erts/emulator/beam/erl_message.c
@@ -33,8 +33,8 @@
 #include "erl_binary.h"
 #include "dtrace-wrapper.h"
 
-ERTS_SCHED_PREF_QUICK_ALLOC_IMPL(message,
-				 ErlMessage,
+ERTS_SCHED_PREF_QUICK_ALLOC_IMPL(message_ref,
+				 ErtsMessageRef,
 				 ERL_MESSAGE_BUF_SZ,
 				 ERTS_ALC_T_MSG_REF)
 
@@ -44,27 +44,20 @@ ERTS_SCHED_PREF_QUICK_ALLOC_IMPL(message,
 #undef HARD_DEBUG
 #endif
 
-
-
-
-#ifdef DEBUG
-static ERTS_INLINE int in_heapfrag(const Eterm* ptr, const ErlHeapFragment *bp)
+void
+init_message(void)
 {
-    return ((unsigned)(ptr - bp->mem) < bp->used_size);
+    init_message_ref_alloc();
 }
-#endif
 
-
-void
-init_message(void)
+void *erts_alloc_message_ref(void)
 {
-    init_message_alloc();
+    return (void *) message_ref_alloc();
 }
 
-void
-free_message(ErlMessage* mp)
+void erts_free_message_ref(void *mp)
 {
-    message_free(mp);
+    message_ref_free((ErtsMessageRef *) mp);
 }
 
 /* Allocate message buffer (size in words) */
@@ -74,7 +67,7 @@ new_message_buffer(Uint size)
     ErlHeapFragment* bp;
     bp = (ErlHeapFragment*) ERTS_HEAP_ALLOC(ERTS_ALC_T_HEAP_FRAG,
 					    ERTS_HEAP_FRAG_SIZE(size));
-    ERTS_INIT_HEAP_FRAG(bp, size);
+    ERTS_INIT_HEAP_FRAG(bp, size, size);
     return bp;
 }
 
@@ -203,83 +196,87 @@ free_message_buffer(ErlHeapFragment* bp)
     }while (bp != NULL);
 }
 
-static ERTS_INLINE void
-link_mbuf_to_proc(Process *proc, ErlHeapFragment *bp)
+void
+erts_cleanup_messages(ErtsMessage *msgp)
 {
-    if (bp) {
-	/* Link the message buffer */
-	bp->next = MBUF(proc);
-	MBUF(proc) = bp;
-	MBUF_SIZE(proc) += bp->used_size;
-	FLAGS(proc) |= F_FORCE_GC;
-
-	/* Move any off_heap's into the process */
-	if (bp->off_heap.first != NULL) {
-	    struct erl_off_heap_header** next_p = &bp->off_heap.first;
-	    while (*next_p != NULL) {
-		next_p = &((*next_p)->next);
+    ErtsMessage *mp = msgp;
+    while (mp) {
+	ErtsMessage *fmp;
+	ErlHeapFragment *bp;
+	if (is_non_value(ERL_MESSAGE_TERM(mp))) {
+	    if (is_not_immed(ERL_MESSAGE_TOKEN(mp))) {
+		bp = (ErlHeapFragment *) mp->data.dist_ext->ext_endp;
+		erts_cleanup_offheap(&bp->off_heap);
 	    }
-	    *next_p = MSO(proc).first;
-	    MSO(proc).first = bp->off_heap.first;
-	    bp->off_heap.first = NULL;
-	    OH_OVERHEAD(&(MSO(proc)), bp->off_heap.overhead);
+	    if (mp->data.dist_ext)
+		erts_free_dist_ext_copy(mp->data.dist_ext);
 	}
+	else {
+	    if (mp->data.attached != ERTS_MSG_COMBINED_HFRAG)
+		bp = mp->data.heap_frag;
+	    else {
+		bp = mp->hfrag.next;
+		erts_cleanup_offheap(&mp->hfrag.off_heap);
+	    }
+	    if (bp)
+		free_message_buffer(bp);
+	}
+	fmp = mp;
+	mp = mp->next;
+	erts_free_message(fmp);
     }
 }
 
-Eterm
-erts_msg_distext2heap(Process *pp,
-		      ErtsProcLocks *plcksp,
-		      ErlHeapFragment **bpp,
-		      Eterm *tokenp,
-		      ErtsDistExternal *dist_extp)
+ErtsMessage *
+erts_realloc_shrink_message(ErtsMessage *mp, Uint sz, Eterm *brefs, Uint brefs_size)
 {
-    Eterm msg;
-    Uint tok_sz = 0;
-    Eterm *hp = NULL;
-    ErtsHeapFactory factory;
-    Sint sz;
-
-    *bpp = NULL;
-    sz = erts_decode_dist_ext_size(dist_extp);
-    if (sz < 0)
-	goto decode_error;
-    if (is_not_nil(*tokenp)) {
-	ErlHeapFragment *heap_frag = erts_dist_ext_trailer(dist_extp);
-	tok_sz = heap_frag->used_size;
-	sz += tok_sz;
-    }
-    if (pp) {
-	ErlOffHeap *ohp;
-	hp = erts_alloc_message_heap(sz, bpp, &ohp, pp, plcksp);
-    }
-    else {
-	*bpp = new_message_buffer(sz);
-	hp = (*bpp)->mem;
-    }
-    erts_factory_message_init(&factory, pp, hp, *bpp);
-    msg = erts_decode_dist_ext(&factory, dist_extp);
-    if (is_non_value(msg))
-	goto decode_error;
-    if (is_not_nil(*tokenp)) {
-	ErlHeapFragment *heap_frag = erts_dist_ext_trailer(dist_extp);
-	hp = erts_produce_heap(&factory, tok_sz, 0);
-	*tokenp = copy_struct(*tokenp, tok_sz, &hp, factory.off_heap);
-	erts_cleanup_offheap(&heap_frag->off_heap);
+    ErtsMessage *nmp = erts_realloc(ERTS_ALC_T_MSG, mp,
+				    sizeof(ErtsMessage) + (sz - 1)*sizeof(Eterm));
+    if (nmp != mp) {
+	Eterm *sp = &mp->hfrag.mem[0];
+	Eterm *ep = sp + sz;
+	Sint offs = &nmp->hfrag.mem[0] - sp;
+	erts_offset_off_heap(&nmp->hfrag.off_heap, offs, sp, ep);
+	erts_offset_heap(&nmp->hfrag.mem[0], sz, offs, sp, ep);
+	if (brefs && brefs_size)
+	    erts_offset_heap_ptr(brefs, brefs_size, offs, sp, ep);
     }
-    erts_free_dist_ext_copy(dist_extp);
-    erts_factory_close(&factory);
-    return msg;
 
- decode_error:
-    if (is_not_nil(*tokenp)) {
-	ErlHeapFragment *heap_frag = erts_dist_ext_trailer(dist_extp);
-	erts_cleanup_offheap(&heap_frag->off_heap);
+    nmp->hfrag.used_size = sz;
+    nmp->hfrag.alloc_size = sz;
+
+    return nmp;
+}
+
+void
+erts_link_mbuf_to_proc(Process *proc, ErlHeapFragment *first_bp)
+{
+    if (first_bp) {
+	ErlHeapFragment *bp = first_bp;
+
+	while (1) {
+	    /* Move any off_heap's into the process */
+	    if (bp->off_heap.first != NULL) {
+		struct erl_off_heap_header** next_p = &bp->off_heap.first;
+		while (*next_p != NULL) {
+		    next_p = &((*next_p)->next);
+		}
+		*next_p = MSO(proc).first;
+		MSO(proc).first = bp->off_heap.first;
+		bp->off_heap.first = NULL;
+		OH_OVERHEAD(&(MSO(proc)), bp->off_heap.overhead);
+	    }
+	    MBUF_SIZE(proc) += bp->used_size;
+	    if (!bp->next)
+		break;
+	    bp = bp->next;
+	}
+
+	/* Link the message buffer */
+	bp->next = MBUF(proc);
+	MBUF(proc) = first_bp;
     }
-    erts_free_dist_ext_copy(dist_extp);
-    *bpp = NULL;
-    return THE_NON_VALUE;
- }
+}
 
 void
 erts_queue_dist_message(Process *rcvr,
@@ -287,7 +284,7 @@ erts_queue_dist_message(Process *rcvr,
 			ErtsDistExternal *dist_ext,
 			Eterm token)
 {
-    ErlMessage* mp;
+    ErtsMessage* mp;
 #ifdef USE_VM_PROBES
     Sint tok_label = 0;
     Sint tok_lastcnt = 0;
@@ -299,7 +296,17 @@ erts_queue_dist_message(Process *rcvr,
 
     ERTS_SMP_LC_ASSERT(*rcvr_locks == erts_proc_lc_my_proc_locks(rcvr));
 
-    mp = message_alloc();
+    mp = erts_alloc_message(0, NULL);
+    mp->data.dist_ext = dist_ext;
+
+    ERL_MESSAGE_TERM(mp) = THE_NON_VALUE;
+#ifdef USE_VM_PROBES
+    ERL_MESSAGE_DT_UTAG(mp) = NIL;
+    if (token == am_have_dt_utag)
+	ERL_MESSAGE_TOKEN(mp) = NIL;
+    else
+#endif
+	ERL_MESSAGE_TOKEN(mp) = token;
 
 #ifdef ERTS_SMP
     if (!(*rcvr_locks & ERTS_PROC_LOCK_MSGQ)) {
@@ -318,58 +325,40 @@ erts_queue_dist_message(Process *rcvr,
 	if (!(*rcvr_locks & ERTS_PROC_LOCK_MSGQ))
 	    erts_smp_proc_unlock(rcvr, ERTS_PROC_LOCK_MSGQ);
 	/* Drop message if receiver is exiting or has a pending exit ... */
-	if (is_not_nil(token)) {
-	    ErlHeapFragment *heap_frag;
-	    heap_frag = erts_dist_ext_trailer(mp->data.dist_ext);
-	    erts_cleanup_offheap(&heap_frag->off_heap);
-	}
-	erts_free_dist_ext_copy(dist_ext);
-	message_free(mp);
+	erts_cleanup_messages(mp);
     }
     else
 #endif
     if (IS_TRACED_FL(rcvr, F_TRACE_RECEIVE)) {
 	/* Ahh... need to decode it in order to trace it... */
-	ErlHeapFragment *mbuf;
-	Eterm msg;
 	if (!(*rcvr_locks & ERTS_PROC_LOCK_MSGQ))
 	    erts_smp_proc_unlock(rcvr, ERTS_PROC_LOCK_MSGQ);
-	message_free(mp);
-	msg = erts_msg_distext2heap(rcvr, rcvr_locks, &mbuf, &token, dist_ext);
-	if (is_value(msg))
+	if (!erts_decode_dist_message(rcvr, *rcvr_locks, mp, 0))
+	    erts_free_message(mp);
+	else {
+	    Eterm msg = ERL_MESSAGE_TERM(mp);
+	    token = ERL_MESSAGE_TOKEN(mp);
 #ifdef USE_VM_PROBES
-            if (DTRACE_ENABLED(message_queued)) {
-                DTRACE_CHARBUF(receiver_name, DTRACE_TERM_BUF_SIZE);
-
-                dtrace_proc_str(rcvr, receiver_name);
-                if (token != NIL && token != am_have_dt_utag) {
-                    tok_label = signed_val(SEQ_TRACE_T_LABEL(token));
-                    tok_lastcnt = signed_val(SEQ_TRACE_T_LASTCNT(token));
-                    tok_serial = signed_val(SEQ_TRACE_T_SERIAL(token));
-                }
-                DTRACE6(message_queued,
-                        receiver_name, size_object(msg), rcvr->msg.len,
-                        tok_label, tok_lastcnt, tok_serial);
-            }
+	    if (DTRACE_ENABLED(message_queued)) {
+		DTRACE_CHARBUF(receiver_name, DTRACE_TERM_BUF_SIZE);
+
+		dtrace_proc_str(rcvr, receiver_name);
+		if (token != NIL && token != am_have_dt_utag) {
+		    tok_label = signed_val(SEQ_TRACE_T_LABEL(token));
+		    tok_lastcnt = signed_val(SEQ_TRACE_T_LASTCNT(token));
+		    tok_serial = signed_val(SEQ_TRACE_T_SERIAL(token));
+		}
+		DTRACE6(message_queued,
+			receiver_name, size_object(msg), rcvr->msg.len,
+			tok_label, tok_lastcnt, tok_serial);
+	    }
 #endif
-	    erts_queue_message(rcvr, rcvr_locks, mbuf, msg, token);
+	    erts_queue_message(rcvr, rcvr_locks, mp, msg, token);
+	}
     }
     else {
 	/* Enqueue message on external format */
 
-	ERL_MESSAGE_TERM(mp) = THE_NON_VALUE;
-#ifdef USE_VM_PROBES
-	ERL_MESSAGE_DT_UTAG(mp) = NIL;
-	if (token == am_have_dt_utag) {
-	    ERL_MESSAGE_TOKEN(mp) = NIL;
-	} else {
-#endif
-	    ERL_MESSAGE_TOKEN(mp) = token;
-#ifdef USE_VM_PROBES
-	}
-#endif
-	mp->next = NULL;
-
 #ifdef USE_VM_PROBES
         if (DTRACE_ENABLED(message_queued)) {
             DTRACE_CHARBUF(receiver_name, DTRACE_TERM_BUF_SIZE);
@@ -388,7 +377,7 @@ erts_queue_dist_message(Process *rcvr,
                     tok_label, tok_lastcnt, tok_serial);
         }
 #endif
-	mp->data.dist_ext = dist_ext;
+
 	LINK_MESSAGE(rcvr, mp);
 
 	if (!(*rcvr_locks & ERTS_PROC_LOCK_MSGQ))
@@ -408,9 +397,9 @@ erts_queue_dist_message(Process *rcvr,
 static Sint
 queue_message(Process *c_p,
 	      Process* receiver,
-	      ErtsProcLocks *receiver_locks,
 	      erts_aint32_t *receiver_state,
-	      ErlHeapFragment* bp,
+	      ErtsProcLocks *receiver_locks,
+	      ErtsMessage* mp,
 	      Eterm message,
 	      Eterm seq_trace_token
 #ifdef USE_VM_PROBES
@@ -419,31 +408,24 @@ queue_message(Process *c_p,
     )
 {
     Sint res;
-    ErlMessage* mp;
     int locked_msgq = 0;
-    erts_aint_t state;
-
-#ifndef ERTS_SMP
-    ASSERT(bp != NULL || receiver->mbuf == NULL);
-#endif
+    erts_aint32_t state;
 
     ERTS_SMP_LC_ASSERT(*receiver_locks == erts_proc_lc_my_proc_locks(receiver));
 
-    mp = message_alloc();
-
-    if (receiver_state)
-	state = *receiver_state;
-    else
-	state = erts_smp_atomic32_read_acqb(&receiver->state);
-
 #ifdef ERTS_SMP
 
-    if (state & (ERTS_PSFLG_EXITING|ERTS_PSFLG_PENDING_EXIT))
-	goto exiting;
-
     if (!(*receiver_locks & ERTS_PROC_LOCK_MSGQ)) {
 	if (erts_smp_proc_trylock(receiver, ERTS_PROC_LOCK_MSGQ) == EBUSY) {
 	    ErtsProcLocks need_locks = ERTS_PROC_LOCK_MSGQ;
+
+	    if (receiver_state)
+		state = *receiver_state;
+	    else
+		state = erts_smp_atomic32_read_nob(&receiver->state);
+	    if (state & (ERTS_PSFLG_EXITING|ERTS_PSFLG_PENDING_EXIT))
+		goto exiting;
+
 	    if (*receiver_locks & ERTS_PROC_LOCK_STATUS) {
 		erts_smp_proc_unlock(receiver, ERTS_PROC_LOCK_STATUS);
 		need_locks |= ERTS_PROC_LOCK_STATUS;
@@ -451,13 +433,12 @@ queue_message(Process *c_p,
 	    erts_smp_proc_lock(receiver, need_locks);
 	}
 	locked_msgq = 1;
-	state = erts_smp_atomic32_read_nob(&receiver->state);
-	if (receiver_state)
-	    *receiver_state = state;
     }
 
 #endif
 
+    state = erts_smp_atomic32_read_nob(&receiver->state);
+
     if (state & (ERTS_PSFLG_PENDING_EXIT|ERTS_PSFLG_EXITING)) {
 #ifdef ERTS_SMP
     exiting:
@@ -465,9 +446,7 @@ queue_message(Process *c_p,
 	/* Drop message if receiver is exiting or has a pending exit... */
 	if (locked_msgq)
 	    erts_smp_proc_unlock(receiver, ERTS_PROC_LOCK_MSGQ);
-	if (bp)
-	    free_message_buffer(bp);
-	message_free(mp);
+	erts_cleanup_messages(mp);
 	return 0;
     }
 
@@ -476,13 +455,9 @@ queue_message(Process *c_p,
 #ifdef USE_VM_PROBES
     ERL_MESSAGE_DT_UTAG(mp) = dt_utag;
 #endif
-    mp->next = NULL;
-    mp->data.heap_frag = bp;
 
-#ifndef ERTS_SMP
     res = receiver->msg.len;
-#else
-    res = receiver->msg_inq.len;
+#ifdef ERTS_SMP
     if (*receiver_locks & ERTS_PROC_LOCK_MAIN) {
 	/*
 	 * We move 'in queue' to 'private queue' and place
@@ -492,7 +467,7 @@ queue_message(Process *c_p,
 	 * we don't need to include the 'in queue' in
 	 * the root set when garbage collecting.
 	 */
-	res += receiver->msg.len;
+	res += receiver->msg_inq.len;
 	ERTS_SMP_MSGQ_MV_INQ2PRIVQ(receiver);
 	LINK_MESSAGE_PRIVQ(receiver, mp);
     }
@@ -544,19 +519,19 @@ queue_message(Process *c_p,
 void
 #ifdef USE_VM_PROBES
 erts_queue_message_probe(Process* receiver, ErtsProcLocks *receiver_locks,
-                         ErlHeapFragment* bp,
+                         ErtsMessage* mp,
                          Eterm message, Eterm seq_trace_token, Eterm dt_utag)
 #else
 erts_queue_message(Process* receiver, ErtsProcLocks *receiver_locks,
-                   ErlHeapFragment* bp,
+                   ErtsMessage* mp,
                    Eterm message, Eterm seq_trace_token)
 #endif
 {
     queue_message(NULL,
 		  receiver,
-		  receiver_locks,
 		  NULL,
-		  bp,
+		  receiver_locks,
+		  mp,
 		  message,
 		  seq_trace_token
 #ifdef USE_VM_PROBES
@@ -565,246 +540,8 @@ erts_queue_message(Process* receiver, ErtsProcLocks *receiver_locks,
 	);
 }
 
-void
-erts_link_mbuf_to_proc(struct process *proc, ErlHeapFragment *bp)
-{
-    Eterm* htop = HEAP_TOP(proc);
-
-    link_mbuf_to_proc(proc, bp);
-    if (htop < HEAP_LIMIT(proc)) {
-	*htop = make_pos_bignum_header(HEAP_LIMIT(proc)-htop-1);
-	HEAP_TOP(proc) = HEAP_LIMIT(proc);
-    }
-}
-
-/*
- * Moves content of message buffer attached to a message into a heap.
- * The message buffer is deallocated.
- */
-void
-erts_move_msg_mbuf_to_heap(Eterm** hpp, ErlOffHeap* off_heap, ErlMessage *msg)
-{
-    struct erl_off_heap_header* oh;
-    Eterm term, token, *fhp, *hp;
-    Sint offs;
-    Uint sz;
-    ErlHeapFragment *bp;
-#ifdef USE_VM_PROBES
-    Eterm utag;
-#endif
-
-#ifdef HARD_DEBUG
-    struct erl_off_heap_header* dbg_oh_start = off_heap->first;
-    Eterm dbg_term, dbg_token;
-    ErlHeapFragment *dbg_bp;
-    Uint *dbg_hp, *dbg_thp_start;
-    Uint dbg_term_sz, dbg_token_sz;
-#ifdef USE_VM_PROBES
-    Eterm dbg_utag;
-    Uint dbg_utag_sz;
-#endif
-#endif
-
-    bp = msg->data.heap_frag;
-    term = ERL_MESSAGE_TERM(msg);
-    token = ERL_MESSAGE_TOKEN(msg);
-#ifdef USE_VM_PROBES
-    utag = ERL_MESSAGE_DT_UTAG(msg);
-#endif
-    if (!bp) {
-#ifdef USE_VM_PROBES
-	ASSERT(is_immed(term) && is_immed(token) && is_immed(utag));
-#else
-	ASSERT(is_immed(term) && is_immed(token));
-#endif
-	return;
-    }
-
-#ifdef HARD_DEBUG
-    dbg_term_sz = size_object(term);
-    dbg_token_sz = size_object(token);
-    dbg_bp = new_message_buffer(dbg_term_sz + dbg_token_sz);
-#ifdef USE_VM_PROBES
-    dbg_utag_sz = size_object(utag);
-    dbg_bp = new_message_buffer(dbg_term_sz + dbg_token_sz + dbg_utag_sz );
-#endif
-    /*ASSERT(dbg_term_sz + dbg_token_sz == erts_msg_used_frag_sz(msg));
-      Copied size may be smaller due to removed SubBins's or garbage.
-      Copied size may be larger due to duplicated shared terms.
-    */
-    dbg_hp = dbg_bp->mem;
-    dbg_term = copy_struct(term, dbg_term_sz, &dbg_hp, &dbg_bp->off_heap);
-    dbg_token = copy_struct(token, dbg_token_sz, &dbg_hp, &dbg_bp->off_heap);
-#ifdef USE_VM_PROBES
-    dbg_utag = copy_struct(utag, dbg_utag_sz, &dbg_hp, &dbg_bp->off_heap);
-#endif
-   dbg_thp_start = *hpp;
-#endif
-
-    if (bp->next != NULL) {
-	move_multi_frags(hpp, off_heap, bp, msg->m, 
-#ifdef USE_VM_PROBES
-			 3
-#else
-			 2
-#endif
-			 );
-	goto copy_done;
-    }
-
-    OH_OVERHEAD(off_heap, bp->off_heap.overhead);
-    sz = bp->used_size;
-
-    ASSERT(is_immed(term) || in_heapfrag(ptr_val(term),bp));
-    ASSERT(is_immed(token) || in_heapfrag(ptr_val(token),bp));
-
-    fhp = bp->mem;
-    hp = *hpp;
-    offs = hp - fhp;
-
-    oh = NULL;
-    while (sz--) {
-	Uint cpy_sz;
-	Eterm val = *fhp++;
-
-	switch (primary_tag(val)) {
-	case TAG_PRIMARY_IMMED1:
-	    *hp++ = val;
-	    break;
-	case TAG_PRIMARY_LIST:
-	case TAG_PRIMARY_BOXED:
-	    ASSERT(in_heapfrag(ptr_val(val), bp));
-	    *hp++ = offset_ptr(val, offs);
-	    break;
-	case TAG_PRIMARY_HEADER:
-	    *hp++ = val;
-	    switch (val & _HEADER_SUBTAG_MASK) {
-	    case ARITYVAL_SUBTAG:
-		break;
-	    case REFC_BINARY_SUBTAG:
-	    case FUN_SUBTAG:
-	    case EXTERNAL_PID_SUBTAG:
-	    case EXTERNAL_PORT_SUBTAG:
-	    case EXTERNAL_REF_SUBTAG:
-		oh = (struct erl_off_heap_header*) (hp-1);
-		cpy_sz = thing_arityval(val);
-		goto cpy_words;
-	    default:
-		cpy_sz = header_arity(val);
-
-	    cpy_words:
-		ASSERT(sz >= cpy_sz);
-		sz -= cpy_sz;
-		while (cpy_sz >= 8) {
-		    cpy_sz -= 8;
-		    *hp++ = *fhp++;
-		    *hp++ = *fhp++;
-		    *hp++ = *fhp++;
-		    *hp++ = *fhp++;
-		    *hp++ = *fhp++;
-		    *hp++ = *fhp++;
-		    *hp++ = *fhp++;
-		    *hp++ = *fhp++;
-		}
-		switch (cpy_sz) {
-		case 7: *hp++ = *fhp++;
-		case 6: *hp++ = *fhp++;
-		case 5: *hp++ = *fhp++;
-		case 4: *hp++ = *fhp++;
-		case 3: *hp++ = *fhp++;
-		case 2: *hp++ = *fhp++;
-		case 1: *hp++ = *fhp++;
-		default: break;
-		}
-		if (oh) {
-		    /* Add to offheap list */
-		    oh->next = off_heap->first;
-		    off_heap->first = oh;
-		    ASSERT(*hpp <= (Eterm*)oh);
-		    ASSERT(hp > (Eterm*)oh);
-		    oh = NULL;
-		}
-		break;
-	    }
-	    break;
-	}
-    }
-
-    ASSERT(bp->used_size == hp - *hpp);
-    *hpp = hp;
-
-    if (is_not_immed(token)) {
-	ASSERT(in_heapfrag(ptr_val(token), bp));
-	ERL_MESSAGE_TOKEN(msg) = offset_ptr(token, offs);
-#ifdef HARD_DEBUG
-	ASSERT(dbg_thp_start <= ptr_val(ERL_MESSAGE_TOKEN(msg)));
-	ASSERT(hp > ptr_val(ERL_MESSAGE_TOKEN(msg)));
-#endif
-    }
-
-    if (is_not_immed(term)) {
-	ASSERT(in_heapfrag(ptr_val(term),bp));
-	ERL_MESSAGE_TERM(msg) = offset_ptr(term, offs);
-#ifdef HARD_DEBUG
-	ASSERT(dbg_thp_start <= ptr_val(ERL_MESSAGE_TERM(msg)));
-	ASSERT(hp > ptr_val(ERL_MESSAGE_TERM(msg)));
-#endif
-    }
-#ifdef USE_VM_PROBES
-    if (is_not_immed(utag)) {
-	ASSERT(in_heapfrag(ptr_val(utag), bp));
-	ERL_MESSAGE_DT_UTAG(msg) = offset_ptr(utag, offs);
-#ifdef HARD_DEBUG
-	ASSERT(dbg_thp_start <= ptr_val(ERL_MESSAGE_DT_UTAG(msg)));
-	ASSERT(hp > ptr_val(ERL_MESSAGE_DT_UTAG(msg)));
-#endif
-    }
-#endif
-
-copy_done:
-
-#ifdef HARD_DEBUG
-    {
-	int i, j;
-	ErlHeapFragment* frag;
-	{
-	    struct erl_off_heap_header* dbg_oh = off_heap->first;
-	    i = j = 0;
-	    while (dbg_oh != dbg_oh_start) {
-		dbg_oh = dbg_oh->next;
-		i++;
-	    }
-	    for (frag=bp; frag; frag=frag->next) {
-		dbg_oh = frag->off_heap.first;
-		while (dbg_oh) {
-		    dbg_oh = dbg_oh->next;
-		    j++;
-		}
-	    }
-	    ASSERT(i == j);
-	}
-    }
-#endif
-	    
-
-    bp->off_heap.first = NULL;
-    free_message_buffer(bp);
-    msg->data.heap_frag = NULL;
-
-#ifdef HARD_DEBUG
-    ASSERT(eq(ERL_MESSAGE_TERM(msg), dbg_term));
-    ASSERT(eq(ERL_MESSAGE_TOKEN(msg), dbg_token));
-#ifdef USE_VM_PROBES
-    ASSERT(eq(ERL_MESSAGE_DT_UTAG(msg), dbg_utag));
-#endif
-    free_message_buffer(dbg_bp);
-#endif
-
-}
-
-
 Uint
-erts_msg_attached_data_size_aux(ErlMessage *msg)
+erts_msg_attached_data_size_aux(ErtsMessage *msg)
 {
     Sint sz;
     ASSERT(is_non_value(ERL_MESSAGE_TERM(msg)));
@@ -833,29 +570,72 @@ erts_msg_attached_data_size_aux(ErlMessage *msg)
     return sz;
 }
 
-void
-erts_move_msg_attached_data_to_heap(ErtsHeapFactory* factory,
-				    ErlMessage *msg)
+ErtsMessage *
+erts_try_alloc_message_on_heap(Process *pp,
+			       erts_aint32_t *psp,
+			       ErtsProcLocks *plp,
+			       Uint sz,
+			       Eterm **hpp,
+			       ErlOffHeap **ohpp,
+			       int *on_heap_p)
 {
-    if (is_value(ERL_MESSAGE_TERM(msg)))
-	erts_move_msg_mbuf_to_heap(&factory->hp, factory->off_heap, msg);
-    else if (msg->data.dist_ext) {
-	ASSERT(msg->data.dist_ext->heap_size >= 0);
-	if (is_not_nil(ERL_MESSAGE_TOKEN(msg))) {
-	    ErlHeapFragment *heap_frag;
-	    heap_frag = erts_dist_ext_trailer(msg->data.dist_ext);
-	    ERL_MESSAGE_TOKEN(msg) = copy_struct(ERL_MESSAGE_TOKEN(msg),
-						 heap_frag->used_size,
-						 &factory->hp,
-						 factory->off_heap);
-	    erts_cleanup_offheap(&heap_frag->off_heap);
+#ifdef ERTS_SMP
+    int locked_main = 0;
+#endif
+    ErtsMessage *mp;
+
+    ASSERT(!(*psp & ERTS_PSFLG_OFF_HEAP_MSGQ));
+
+    if (
+#if defined(ERTS_SMP)
+	*plp & ERTS_PROC_LOCK_MAIN
+#else
+	1
+#endif
+	) {
+#ifdef ERTS_SMP
+    try_on_heap:
+#endif
+	if ((*psp & (ERTS_PSFLG_EXITING|ERTS_PSFLG_PENDING_EXIT))
+	    || (pp->flags & F_DISABLE_GC)
+	    || HEAP_LIMIT(pp) - HEAP_TOP(pp) <= sz) {
+	    /*
+	     * The heap is either potentially in an inconsistent
+	     * state, or not large enough.
+	     */
+#ifdef ERTS_SMP
+	    if (locked_main) {
+		*plp &= ~ERTS_PROC_LOCK_MAIN;
+		erts_smp_proc_unlock(pp, ERTS_PROC_LOCK_MAIN);
+	    }
+#endif
+	    goto in_message_fragment;
 	}
-	ERL_MESSAGE_TERM(msg) = erts_decode_dist_ext(factory,
-						     msg->data.dist_ext);
-	erts_free_dist_ext_copy(msg->data.dist_ext);
-	msg->data.dist_ext = NULL;
+
+	*hpp = HEAP_TOP(pp);
+	HEAP_TOP(pp) = *hpp + sz;
+	*ohpp = &MSO(pp);
+	mp = erts_alloc_message(0, NULL);
+	mp->data.attached = NULL;
+	*on_heap_p = !0;
+    }
+#ifdef ERTS_SMP
+    else if (erts_smp_proc_trylock(pp, ERTS_PROC_LOCK_MAIN) == 0) {
+	locked_main = 1;
+	*psp = erts_smp_atomic32_read_nob(&pp->state);
+	*plp |= ERTS_PROC_LOCK_MAIN;
+	goto try_on_heap;
+    }
+#endif
+    else {
+    in_message_fragment:
+
+	mp = erts_alloc_message(sz, hpp);
+	*ohpp = sz == 0 ? NULL : &mp->hfrag.off_heap;
+	*on_heap_p = 0;
     }
-    /* else: bad external detected when calculating size */
+
+    return mp;
 }
 
 /*
@@ -870,7 +650,8 @@ erts_send_message(Process* sender,
 		  unsigned flags)
 {
     Uint msize;
-    ErlHeapFragment* bp = NULL;
+    ErtsMessage* mp;
+    ErlOffHeap *ohp;
     Eterm token = NIL;
     Sint res = 0;
 #ifdef USE_VM_PROBES
@@ -879,27 +660,31 @@ erts_send_message(Process* sender,
     Sint tok_label = 0;
     Sint tok_lastcnt = 0;
     Sint tok_serial = 0;
+    Eterm utag = NIL;
 #endif
+    erts_aint32_t receiver_state;
     BM_STOP_TIMER(system);
     BM_MESSAGE(message,sender,receiver);
     BM_START_TIMER(send);
 
  #ifdef USE_VM_PROBES
     *sender_name = *receiver_name = '\0';
-   if (DTRACE_ENABLED(message_send)) {
+    if (DTRACE_ENABLED(message_send)) {
         erts_snprintf(sender_name, sizeof(DTRACE_CHARBUF_NAME(sender_name)),
 		      "%T", sender->common.id);
         erts_snprintf(receiver_name, sizeof(DTRACE_CHARBUF_NAME(receiver_name)),
 		      "%T", receiver->common.id);
     }
 #endif
+
+    receiver_state = erts_smp_atomic32_read_nob(&receiver->state);
+
     if (SEQ_TRACE_TOKEN(sender) != NIL && !(flags & ERTS_SND_FLG_NO_SEQ_TRACE)) {
         Eterm* hp;
 	Eterm stoken = SEQ_TRACE_TOKEN(sender);
 	Uint seq_trace_size = 0;
 #ifdef USE_VM_PROBES
 	Uint dt_utag_size = 0;
-	Eterm utag = NIL;
 #endif
 
 	BM_SWAP_TIMER(send,size);
@@ -923,23 +708,32 @@ erts_send_message(Process* sender,
 	}
 #endif
 
-	bp = new_message_buffer(msize + seq_trace_size 
+	mp = erts_alloc_message_heap_state(receiver,
+					   &receiver_state,
+					   receiver_locks,
+					   (msize
 #ifdef USE_VM_PROBES
-				+ dt_utag_size
+					    + dt_utag_size
 #endif
-				);
-	hp = bp->mem;
+					    + seq_trace_size),
+					   &hp,
+					   &ohp);
 
         BM_SWAP_TIMER(send,copy);
-	token = copy_struct(stoken,
-			    seq_trace_size,
-			    &hp,
-			    &bp->off_heap);
+	if (is_immed(stoken))
+	    token = stoken;
+	else
+	    token = copy_struct(stoken, seq_trace_size, &hp, ohp);
+
+	if (is_not_immed(message))
+	    message = copy_struct(message, msize, &hp, ohp);
 
-	message = copy_struct(message, msize, &hp, &bp->off_heap);
 #ifdef USE_VM_PROBES
 	if (DT_UTAG_FLAGS(sender) & DT_UTAG_SPREADING) {
-	    utag = copy_struct(DT_UTAG(sender), dt_utag_size, &hp, &bp->off_heap);
+	    if (is_immed(DT_UTAG(sender)))
+		utag = DT_UTAG(sender);
+	    else
+		utag = copy_struct(DT_UTAG(sender), dt_utag_size, ohp);
 #ifdef DTRACE_TAG_HARDDEBUG
 	    erts_fprintf(stderr,
 			 "Dtrace -> (%T) Spreading tag (%T) with "
@@ -961,101 +755,49 @@ erts_send_message(Process* sender,
 		    msize, tok_label, tok_lastcnt, tok_serial);
         }
 #endif
-        res = queue_message(NULL,
-			    receiver,
-			    receiver_locks,
-			    NULL,
-			    bp,
-			    message,
-			    token
-#ifdef USE_VM_PROBES
-			    , utag
-#endif
-	    );
-        BM_SWAP_TIMER(send,system);
-    } else if (sender == receiver) {
-	/* Drop message if receiver has a pending exit ... */
-#ifdef ERTS_SMP
-	ErtsProcLocks need_locks = (~(*receiver_locks)
-				    & (ERTS_PROC_LOCK_MSGQ
-				       | ERTS_PROC_LOCK_STATUS));
-	if (need_locks) {
-	    *receiver_locks |= need_locks;
-	    if (erts_smp_proc_trylock(receiver, need_locks) == EBUSY) {
-		if (need_locks == ERTS_PROC_LOCK_MSGQ) {
-		    erts_smp_proc_unlock(receiver, ERTS_PROC_LOCK_STATUS);
-		    need_locks = ERTS_PROC_LOCK_MSGQ|ERTS_PROC_LOCK_STATUS;
-		}
-		erts_smp_proc_lock(receiver, need_locks);
-	    }
-	}
-	if (!ERTS_PROC_PENDING_EXIT(receiver))
-#endif
-	{
-	    ErlMessage* mp = message_alloc();
-
-            DTRACE6(message_send, sender_name, receiver_name,
-                    size_object(message), tok_label, tok_lastcnt, tok_serial);
-	    mp->data.attached = NULL;
-	    ERL_MESSAGE_TERM(mp) = message;
-	    ERL_MESSAGE_TOKEN(mp) = NIL;
-#ifdef USE_VM_PROBES
-	    ERL_MESSAGE_DT_UTAG(mp) = NIL;
-#endif
-	    mp->next = NULL;
-	    /*
-	     * We move 'in queue' to 'private queue' and place
-	     * message at the end of 'private queue' in order
-	     * to ensure that the 'in queue' doesn't contain
-	     * references into the heap. By ensuring this,
-	     * we don't need to include the 'in queue' in
-	     * the root set when garbage collecting.
-	     */
-	    
-	    ERTS_SMP_MSGQ_MV_INQ2PRIVQ(receiver);
-	    LINK_MESSAGE_PRIVQ(receiver, mp);
-
-	    res = receiver->msg.len;
-
-	    if (IS_TRACED_FL(receiver, F_TRACE_RECEIVE)) {
-		trace_receive(receiver, message);
-	    }
-	}
-        BM_SWAP_TIMER(send,system);
     } else {
-	ErlOffHeap *ohp;
         Eterm *hp;
-	erts_aint32_t state;
 
-	BM_SWAP_TIMER(send,size);
-	msize = size_object(message);
-	BM_SWAP_TIMER(size,send);
-	hp = erts_alloc_message_heap_state(msize,
-					   &bp,
-					   &ohp,
-					   receiver,
-					   receiver_locks,
-					   &state);
-	BM_SWAP_TIMER(send,copy);
-	message = copy_struct(message, msize, &hp, ohp);
-	BM_MESSAGE_COPIED(msz);
-	BM_SWAP_TIMER(copy,send);
+	if (receiver == sender && !(receiver_state & ERTS_PSFLG_OFF_HEAP_MSGQ)) {
+	    mp = erts_alloc_message(0, NULL);
+	    msize = 0;
+	}
+	else {
+	    BM_SWAP_TIMER(send,size);
+	    msize = size_object(message);
+	    BM_SWAP_TIMER(size,send);
+
+	    mp = erts_alloc_message_heap_state(receiver,
+					       &receiver_state,
+					       receiver_locks,
+					       msize,
+					       &hp,
+					       &ohp);
+	    BM_SWAP_TIMER(send,copy);
+	    if (is_not_immed(message))
+		message = copy_struct(message, msize, &hp, ohp);
+	    BM_MESSAGE_COPIED(msz);
+	    BM_SWAP_TIMER(copy,send);
+	}
         DTRACE6(message_send, sender_name, receiver_name,
                 msize, tok_label, tok_lastcnt, tok_serial);
-	res = queue_message(sender,
-			    receiver,
-			    receiver_locks,
-			    &state,
-			    bp,
-			    message,
-			    token
+    }
+
+    res = queue_message(sender,
+			receiver,
+			&receiver_state,
+			receiver_locks,
+			mp,
+			message,
+			token
 #ifdef USE_VM_PROBES
-			    , NIL
+			, utag
 #endif
-	    );
-        BM_SWAP_TIMER(send,system);
-    }
-   return res;
+	);
+
+    BM_SWAP_TIMER(send,system);
+    
+    return res;
 }
 
 /*
@@ -1075,7 +817,8 @@ erts_deliver_exit_message(Eterm from, Process *to, ErtsProcLocks *to_locksp,
     Uint sz_from;
     Eterm* hp;
     Eterm temptoken;
-    ErlHeapFragment* bp = NULL;
+    ErtsMessage* mp;
+    ErlOffHeap *ohp;
 
     if (token != NIL
 #ifdef USE_VM_PROBES
@@ -1087,36 +830,483 @@ erts_deliver_exit_message(Eterm from, Process *to, ErtsProcLocks *to_locksp,
 	sz_reason = size_object(reason);
 	sz_token = size_object(token);
 	sz_from = size_object(from);
-	bp = new_message_buffer(sz_reason + sz_from + sz_token + 4);
-	hp = bp->mem;
-	mess = copy_struct(reason, sz_reason, &hp, &bp->off_heap);
-	from_copy = copy_struct(from, sz_from, &hp, &bp->off_heap);
+	mp = erts_alloc_message_heap(to, to_locksp,
+				     sz_reason + sz_from + sz_token + 4,
+				     &hp, &ohp);
+	mess = copy_struct(reason, sz_reason, &hp, ohp);
+	from_copy = copy_struct(from, sz_from, &hp, ohp);
 	save = TUPLE3(hp, am_EXIT, from_copy, mess);
 	hp += 4;
 	/* the trace token must in this case be updated by the caller */
 	seq_trace_output(token, save, SEQ_TRACE_SEND, to->common.id, NULL);
-	temptoken = copy_struct(token, sz_token, &hp, &bp->off_heap);
-	erts_queue_message(to, to_locksp, bp, save, temptoken);
+	temptoken = copy_struct(token, sz_token, &hp, ohp);
+	erts_queue_message(to, to_locksp, mp, save, temptoken);
     } else {
-	ErlOffHeap *ohp;
 	sz_reason = size_object(reason);
 	sz_from = IS_CONST(from) ? 0 : size_object(from);
 
-	hp = erts_alloc_message_heap(sz_reason+sz_from+4,
-				     &bp,
-				     &ohp,
-				     to,
-				     to_locksp);
+	mp = erts_alloc_message_heap(to, to_locksp,
+				     sz_reason+sz_from+4, &hp, &ohp);
 
 	mess = copy_struct(reason, sz_reason, &hp, ohp);
 	from_copy = (IS_CONST(from)
 		     ? from
 		     : copy_struct(from, sz_from, &hp, ohp));
 	save = TUPLE3(hp, am_EXIT, from_copy, mess);
-	erts_queue_message(to, to_locksp, bp, save, NIL);
+	erts_queue_message(to, to_locksp, mp, save, NIL);
     }
 }
 
+void erts_save_message_in_proc(Process *p, ErtsMessage *msgp)
+{
+    ErlHeapFragment *hfp;
+
+    if (msgp->data.attached == ERTS_MSG_COMBINED_HFRAG)
+	hfp = &msgp->hfrag;
+    else if (msgp->data.attached) {
+	hfp = msgp->data.heap_frag;
+    }
+    else {
+	erts_free_message(msgp);
+	return; /* Nothing to save */
+    }
+
+    while (1) {
+	struct erl_off_heap_header *ohhp = hfp->off_heap.first;
+	if (ohhp) {
+	    for ( ; ohhp->next; ohhp = ohhp->next)
+		;
+	    ohhp->next = p->off_heap.first;
+	    p->off_heap.first = hfp->off_heap.first;
+	    hfp->off_heap.first = NULL;
+	}
+	p->off_heap.overhead += hfp->off_heap.overhead;
+	hfp->off_heap.overhead = 0;
+	p->mbuf_sz += hfp->used_size;
+
+	if (!hfp->next)
+	    break;
+	hfp = hfp->next;
+    }
+
+    msgp->next = p->msg_frag;
+    p->msg_frag = msgp;
+}
+
+Sint
+erts_move_messages_off_heap(Process *c_p)
+{
+    int reds = 1;
+    /*
+     * Move all messages off heap. This *only* occurs when the
+     * process had off heap message disabled and just enabled
+     * it...
+     */
+    ErtsMessage *mp;
+
+    reds += c_p->msg.len / 10;
+
+    ASSERT(erts_smp_atomic32_read_nob(&c_p->state)
+	   & ERTS_PSFLG_OFF_HEAP_MSGQ);
+    ASSERT(c_p->flags & F_OFF_HEAP_MSGQ_CHNG);
+
+    for (mp = c_p->msg.first; mp; mp = mp->next) {
+	Uint msg_sz, token_sz;
+#ifdef USE_VM_PROBES
+	Uint utag_sz;
+#endif
+	Eterm *hp;
+	ErlHeapFragment *hfrag;
+
+	if (mp->data.attached)
+	    continue;
+
+	if (is_immed(ERL_MESSAGE_TERM(mp))
+#ifdef USE_VM_PROBES
+	    && is_immed(ERL_MESSAGE_DT_UTAG(mp))
+#endif
+	    && is_not_immed(ERL_MESSAGE_TOKEN(mp)))
+	    continue;
+
+	/*
+	 * The message refers into the heap. Copy the message
+	 * from the heap into a heap fragment and attach
+	 * it to the message...
+	 */
+	msg_sz = size_object(ERL_MESSAGE_TERM(mp));
+#ifdef USE_VM_PROBES
+	utag_sz = size_object(ERL_MESSAGE_DT_UTAG(mp));
+#endif
+	token_sz = size_object(ERL_MESSAGE_TOKEN(mp));
+
+	hfrag = new_message_buffer(msg_sz
+#ifdef USE_VM_PROBES
+				   + utag_sz
+#endif
+				   + token_sz);
+	hp = hfrag->mem;
+	if (is_not_immed(ERL_MESSAGE_TERM(mp)))
+	    ERL_MESSAGE_TERM(mp) = copy_struct(ERL_MESSAGE_TERM(mp),
+					       msg_sz, &hp,
+					       &hfrag->off_heap);
+	if (is_not_immed(ERL_MESSAGE_TOKEN(mp)))
+	    ERL_MESSAGE_TOKEN(mp) = copy_struct(ERL_MESSAGE_TOKEN(mp),
+						token_sz, &hp,
+						&hfrag->off_heap);
+#ifdef USE_VM_PROBES
+	if (is_not_immed(ERL_MESSAGE_DT_UTAG(mp)))
+	    ERL_MESSAGE_DT_UTAG(mp) = copy_struct(ERL_MESSAGE_DT_UTAG(mp),
+						  utag_sz, &hp,
+						  &hfrag->off_heap);
+#endif
+	mp->data.heap_frag = hfrag;
+	reds += 1;
+    }
+
+    return reds;
+}
+
+Sint
+erts_complete_off_heap_message_queue_change(Process *c_p)
+{
+    int reds = 1;
+
+    ERTS_SMP_LC_ASSERT(ERTS_PROC_LOCK_MAIN == erts_proc_lc_my_proc_locks(c_p));
+    ASSERT(c_p->flags & F_OFF_HEAP_MSGQ_CHNG);
+    ASSERT(erts_smp_atomic32_read_nob(&c_p->state) & ERTS_PSFLG_OFF_HEAP_MSGQ);
+
+    /*
+     * This job was first initiated when the process changed
+     * "off heap message queue" state from false to true. Since
+     * then ERTS_PSFLG_OFF_HEAP_MSGQ has been set. However, the
+     * state change might have been changed again (multiple times)
+     * since then. Check users last requested state (the flag
+     * F_OFF_HEAP_MSGQ), and make the state consistent with that.
+     */
+
+    if (!(c_p->flags & F_OFF_HEAP_MSGQ))
+	erts_smp_atomic32_read_band_nob(&c_p->state,
+					~ERTS_PSFLG_OFF_HEAP_MSGQ);
+    else {
+	reds += 2;
+	erts_smp_proc_lock(c_p, ERTS_PROC_LOCK_MSGQ);
+	ERTS_SMP_MSGQ_MV_INQ2PRIVQ(c_p);
+	erts_smp_proc_unlock(c_p, ERTS_PROC_LOCK_MSGQ);
+	reds += erts_move_messages_off_heap(c_p);
+    }
+    c_p->flags &= ~F_OFF_HEAP_MSGQ_CHNG;
+    return reds;
+}
+
+typedef struct {
+    Eterm pid;
+    ErtsThrPrgrLaterOp lop;
+} ErtsChangeOffHeapMessageQueue;
+
+static void
+change_off_heap_msgq(void *vcohmq)
+{
+    ErtsChangeOffHeapMessageQueue *cohmq;
+    /*
+     * Now we've waited thread progress which ensures that all
+     * messages to the process are enqueued off heap. Schedule
+     * completion of this change as a system task on the process
+     * itself. This in order to avoid lock contention on its
+     * main lock. We will be called in
+     * erts_complete_off_heap_message_queue_change() (above) when
+     * the system task has been selected for execution.
+     */
+    cohmq = (ErtsChangeOffHeapMessageQueue *) vcohmq;
+    erts_schedule_complete_off_heap_message_queue_change(cohmq->pid);
+    erts_free(ERTS_ALC_T_MSGQ_CHNG, vcohmq);
+}
+
+Eterm
+erts_change_off_heap_message_queue_state(Process *c_p, int enable)
+{
+
+#ifdef DEBUG
+    if (c_p->flags & F_OFF_HEAP_MSGQ) {
+	ASSERT(erts_smp_atomic32_read_nob(&c_p->state)
+	       & ERTS_PSFLG_OFF_HEAP_MSGQ);
+    }
+    else {
+	if (c_p->flags & F_OFF_HEAP_MSGQ_CHNG) {
+	    ASSERT(erts_smp_atomic32_read_nob(&c_p->state)
+		   & ERTS_PSFLG_OFF_HEAP_MSGQ);
+	}
+	else {
+	    ASSERT(!(erts_smp_atomic32_read_nob(&c_p->state)
+		     & ERTS_PSFLG_OFF_HEAP_MSGQ));
+	}
+    }
+#endif
+
+    if (c_p->flags & F_OFF_HEAP_MSGQ) {
+	/* Off heap message queue is enabled */
+
+	if (!enable) {
+	    c_p->flags &= ~F_OFF_HEAP_MSGQ;
+	    /*
+	     * We are not allowed to clear ERTS_PSFLG_OFF_HEAP_MSGQ
+	     * if a change is ongoing. It will be adjusted when the
+	     * change completes...
+	     */
+	    if (!(c_p->flags & F_OFF_HEAP_MSGQ_CHNG)) {
+		/* Safe to clear ERTS_PSFLG_OFF_HEAP_MSGQ... */
+		erts_smp_atomic32_read_band_nob(&c_p->state,
+						~ERTS_PSFLG_OFF_HEAP_MSGQ);
+	    }
+	}
+
+	return am_true; /* Old state */
+    }
+
+    /* Off heap message queue is disabled */
+
+    if (enable) {
+	c_p->flags |= F_OFF_HEAP_MSGQ;
+	/*
+	 * We do not have to schedule a change if
+	 * we have an ongoing change...
+	 */
+	if (!(c_p->flags & F_OFF_HEAP_MSGQ_CHNG)) {
+	    ErtsChangeOffHeapMessageQueue *cohmq;
+	    /*
+	     * Need to set ERTS_PSFLG_OFF_HEAP_MSGQ and wait
+	     * thread progress before completing the change in
+	     * order to ensure that all senders observe that
+	     * messages should be passed off heap. When the
+	     * change has completed, GC does not need to inspect
+	     * the message queue at all.
+	     */
+	    erts_smp_atomic32_read_bor_nob(&c_p->state,
+					   ERTS_PSFLG_OFF_HEAP_MSGQ);
+	    c_p->flags |= F_OFF_HEAP_MSGQ_CHNG;
+	    cohmq = erts_alloc(ERTS_ALC_T_MSGQ_CHNG,
+			       sizeof(ErtsChangeOffHeapMessageQueue));
+	    cohmq->pid = c_p->common.id;
+	    erts_schedule_thr_prgr_later_op(change_off_heap_msgq,
+					    (void *) cohmq,
+					    &cohmq->lop);
+	}
+    }
+
+    return am_false; /* Old state */
+}
+
+int
+erts_decode_dist_message(Process *proc, ErtsProcLocks proc_locks,
+			 ErtsMessage *msgp, int force_off_heap)
+{
+    ErtsHeapFactory factory;
+    Eterm msg;
+    ErlHeapFragment *bp;
+    Sint need;
+    int decode_in_heap_frag;
+
+    decode_in_heap_frag = (force_off_heap
+			   || !(proc_locks & ERTS_PROC_LOCK_MAIN)
+			   || (proc->flags & F_OFF_HEAP_MSGQ));
+
+    if (msgp->data.dist_ext->heap_size >= 0)
+	need = msgp->data.dist_ext->heap_size;
+    else {
+	need = erts_decode_dist_ext_size(msgp->data.dist_ext);
+	if (need < 0) {
+	    /* bad msg; remove it... */
+	    if (is_not_immed(ERL_MESSAGE_TOKEN(msgp))) {
+		bp = erts_dist_ext_trailer(msgp->data.dist_ext);
+		erts_cleanup_offheap(&bp->off_heap);
+	    }
+	    erts_free_dist_ext_copy(msgp->data.dist_ext);
+	    msgp->data.dist_ext = NULL;
+	    return 0;
+	}
+
+	msgp->data.dist_ext->heap_size = need;
+    }
+
+    if (is_not_immed(ERL_MESSAGE_TOKEN(msgp))) {
+	bp = erts_dist_ext_trailer(msgp->data.dist_ext);
+	need += bp->used_size;
+    }
+
+    if (decode_in_heap_frag)
+	erts_factory_heap_frag_init(&factory, new_message_buffer(need));
+    else
+	erts_factory_proc_prealloc_init(&factory, proc, need);
+
+    ASSERT(msgp->data.dist_ext->heap_size >= 0);
+    if (is_not_immed(ERL_MESSAGE_TOKEN(msgp))) {
+	ErlHeapFragment *heap_frag;
+	heap_frag = erts_dist_ext_trailer(msgp->data.dist_ext);
+	ERL_MESSAGE_TOKEN(msgp) = copy_struct(ERL_MESSAGE_TOKEN(msgp),
+					      heap_frag->used_size,
+					      &factory.hp,
+					      factory.off_heap);
+	erts_cleanup_offheap(&heap_frag->off_heap);
+    }
+
+    msg = erts_decode_dist_ext(&factory, msgp->data.dist_ext);
+    ERL_MESSAGE_TERM(msgp) = msg;
+    erts_free_dist_ext_copy(msgp->data.dist_ext);
+    msgp->data.attached = NULL;
+
+    if (is_non_value(msg)) {
+	erts_factory_undo(&factory);
+	return 0;
+    }
+
+    erts_factory_trim_and_close(&factory, msgp->m,
+				ERL_MESSAGE_REF_ARRAY_SZ);
+
+    ASSERT(!msgp->data.heap_frag);
+
+    if (decode_in_heap_frag)
+	msgp->data.heap_frag = factory.heap_frags;
+
+    return 1;
+}
+
+/*
+ * ERTS_INSPECT_MSGQ_KEEP_OH_MSGS == 0 will move off heap messages
+ * into the heap of the inspected process if off_heap_message_queue
+ * is false when process_info(_, messages) is called. That is, the
+ * following GC will have more data in the rootset compared to the
+ * scenario when process_info(_, messages) had not been called.
+ *
+ * ERTS_INSPECT_MSGQ_KEEP_OH_MSGS != 0 will keep off heap messages
+ * off heap when process_info(_, messages) is called regardless of
+ * the off_heap_message_queue setting of the process. That is, it
+ * will change the following execution of the process as little as
+ * possible.
+ */
+#define ERTS_INSPECT_MSGQ_KEEP_OH_MSGS 1
+
+Uint
+erts_prep_msgq_for_inspection(Process *c_p, Process *rp,
+			      ErtsProcLocks rp_locks, ErtsMessageInfo *mip)
+{
+    Uint tot_heap_size;
+    ErtsMessage* mp;
+    Sint i;
+    int self_on_heap;
+    
+    /*
+     * Prepare the message queue for inspection
+     * by process_info().
+     *
+     *
+     * - Decode all messages on external format
+     * - Remove all corrupt dist messages from queue
+     * - Save pointer to, and heap size need of each
+     *   message in the mip array.
+     * - Return total heap size need for all messages
+     *   that needs to be copied.
+     *
+     * If ERTS_INSPECT_MSGQ_KEEP_OH_MSGS == 0:
+     * - In case off heap messages is disabled and
+     *   we are inspecting our own queue, move all
+     *   off heap data into the heap.
+     */
+
+    self_on_heap = c_p == rp && !(c_p->flags & F_OFF_HEAP_MSGQ);
+
+    tot_heap_size = 0;
+    i = 0;
+    mp = rp->msg.first;
+    while (mp) {
+	Eterm msg = ERL_MESSAGE_TERM(mp);
+
+	mip[i].size = 0;
+
+	if (is_non_value(msg)) {
+	    /* Dist message on external format; decode it... */
+	    if (mp->data.attached)
+		erts_decode_dist_message(rp, rp_locks, mp,
+					 ERTS_INSPECT_MSGQ_KEEP_OH_MSGS);
+
+	    msg = ERL_MESSAGE_TERM(mp);
+
+	    if (is_non_value(msg)) {
+		ErtsMessage **mpp;
+		ErtsMessage *bad_mp = mp;
+		/*
+		 * Bad distribution message; remove
+		 * it from the queue...
+		 */
+		ASSERT(!mp->data.attached);
+
+		mpp = i == 0 ? &rp->msg.first : &mip[i-1].msgp->next;
+
+		if (rp->msg.save == &bad_mp->next)
+		    rp->msg.save = mpp;
+		if (rp->msg.last == &bad_mp->next)
+		    rp->msg.last = mpp;
+		mp = mp->next;
+		*mpp = mp;
+		rp->msg.len--;
+		bad_mp->next = NULL;
+		erts_cleanup_messages(bad_mp);
+		continue;
+	    }
+	}
+
+	ASSERT(is_value(msg));
+
+#if ERTS_INSPECT_MSGQ_KEEP_OH_MSGS
+	if (is_not_immed(msg) && (!self_on_heap || mp->data.attached)) {
+	    Uint sz = size_object(msg);
+	    mip[i].size = sz;
+	    tot_heap_size += sz;
+	}
+#else
+	if (self_on_heap) {
+	    if (mp->data.attached) {
+		ErtsMessage *tmp = NULL;
+		if (mp->data.attached != ERTS_MSG_COMBINED_HFRAG) {
+		    erts_link_mbuf_to_proc(rp, mp->data.heap_frag);
+		    mp->data.attached = NULL;
+		}
+		else {
+		    /*
+		     * Need to replace the message reference since
+		     * we will get references to the message data
+		     * from the heap...
+		     */
+		    ErtsMessage **mpp;
+		    tmp = erts_alloc_message(0, NULL);
+		    sys_memcpy((void *) tmp->m, (void *) mp->m,
+			       sizeof(Eterm)*ERL_MESSAGE_REF_ARRAY_SZ); 
+		    mpp = i == 0 ? &rp->msg.first : &mip[i-1].msgp->next;
+		    tmp->next = mp->next;
+		    if (rp->msg.save == &mp->next)
+			rp->msg.save = &tmp->next;
+		    if (rp->msg.last == &mp->next)
+			rp->msg.last = &tmp->next;
+		    *mpp = tmp;
+		    erts_save_message_in_proc(rp, mp);
+		    mp = tmp;
+		}
+	    }
+	}
+	else if (is_not_immed(msg)) {
+	    Uint sz = size_object(msg);
+	    mip[i].size = sz;
+	    tot_heap_size += sz;
+	}
+
+#endif
+
+	mip[i].msgp = mp;
+	i++;
+	mp = mp->next;
+    }
+
+    return tot_heap_size;
+}
+
 void erts_factory_proc_init(ErtsHeapFactory* factory,
 			    Process* p)
 {
@@ -1127,47 +1317,138 @@ void erts_factory_proc_prealloc_init(ErtsHeapFactory* factory,
 				     Process* p,
 				     Sint size)
 {
+    ErlHeapFragment *bp = p->mbuf;
     factory->mode     = FACTORY_HALLOC;
     factory->p        = p;
     factory->hp_start = HAlloc(p, size);
     factory->hp       = factory->hp_start;
     factory->hp_end   = factory->hp_start + size;
     factory->off_heap = &p->off_heap;
+    factory->message  = NULL;
     factory->off_heap_saved.first    = p->off_heap.first;
     factory->off_heap_saved.overhead = p->off_heap.overhead;
-    factory->heap_frags_saved = p->mbuf;
+    factory->heap_frags_saved = bp;
+    factory->heap_frags_saved_used = bp ? bp->used_size : 0;
     factory->heap_frags = NULL; /* not used */
     factory->alloc_type = 0; /* not used */
 }
 
-void erts_factory_message_init(ErtsHeapFactory* factory,
-			       Process* rp,
-			       Eterm* hp,
-			       ErlHeapFragment* bp)
+void erts_factory_heap_frag_init(ErtsHeapFactory* factory,
+				 ErlHeapFragment* bp)
+{
+    factory->mode     = FACTORY_HEAP_FRAGS;
+    factory->p        = NULL;
+    factory->hp_start = bp->mem;
+    factory->hp       = bp->mem;
+    factory->hp_end   = bp->mem + bp->alloc_size;
+    factory->off_heap = &bp->off_heap;
+    factory->message  = NULL;
+    factory->heap_frags = bp;
+    factory->heap_frags_saved = NULL;
+    factory->heap_frags_saved_used = 0;
+    factory->alloc_type = ERTS_ALC_T_HEAP_FRAG;
+    ASSERT(!bp->next);
+    factory->off_heap_saved.first    = factory->off_heap->first;
+    factory->off_heap_saved.overhead = factory->off_heap->overhead;
+
+    ASSERT(factory->hp >= factory->hp_start && factory->hp <= factory->hp_end);
+}
+
+
+ErtsMessage *
+erts_factory_message_create(ErtsHeapFactory* factory,
+			    Process *proc,
+			    ErtsProcLocks *proc_locksp,
+			    Uint sz)
+{
+    Eterm *hp;
+    ErlOffHeap *ohp;
+    ErtsMessage *msgp;
+    int on_heap;
+    erts_aint32_t state;
+
+    state = erts_smp_atomic32_read_nob(&proc->state);
+
+    if (state & ERTS_PSFLG_OFF_HEAP_MSGQ) {
+	msgp = erts_alloc_message(sz, &hp);
+	ohp = sz == 0 ? NULL : &msgp->hfrag.off_heap;
+	on_heap = 0;
+    }
+    else {
+	msgp = erts_try_alloc_message_on_heap(proc, &state,
+					      proc_locksp,
+					      sz, &hp, &ohp,
+					      &on_heap);
+    }
+
+    if (on_heap) {
+	ASSERT(*proc_locksp & ERTS_PROC_LOCK_MAIN);
+	ASSERT(ohp == &proc->off_heap);
+	factory->mode = FACTORY_HALLOC;
+	factory->p = proc;
+	factory->heap_frags_saved = proc->mbuf;
+	factory->heap_frags_saved_used = proc->mbuf ? proc->mbuf->used_size : 0;
+    }
+    else {
+	factory->mode = FACTORY_MESSAGE;
+	factory->p = NULL;
+	factory->heap_frags_saved = NULL;
+	factory->heap_frags_saved_used = 0;
+
+	if (msgp->data.attached == ERTS_MSG_COMBINED_HFRAG) {
+	    ASSERT(!msgp->hfrag.next);
+	    factory->heap_frags = NULL;
+	}
+	else {
+	    ASSERT(!msgp->data.heap_frag
+		   || !msgp->data.heap_frag->next);
+	    factory->heap_frags = msgp->data.heap_frag;
+	}
+    }
+    factory->hp_start = hp;
+    factory->hp       = hp;
+    factory->hp_end   = hp + sz;
+    factory->message  = msgp;
+    factory->off_heap = ohp;
+    factory->alloc_type = ERTS_ALC_T_HEAP_FRAG;
+    if (ohp) {
+	factory->off_heap_saved.first    = ohp->first;
+	factory->off_heap_saved.overhead = ohp->overhead;
+    }
+    else {
+	factory->off_heap_saved.first    = NULL;
+	factory->off_heap_saved.overhead = 0;
+    }
+
+    ASSERT(factory->hp >= factory->hp_start && factory->hp <= factory->hp_end);
+
+    return msgp;
+}
+
+void erts_factory_selfcontained_message_init(ErtsHeapFactory* factory,
+					     ErtsMessage *msgp,
+					     Eterm *hp)
 {
-    if (bp) {
-	factory->mode     = FACTORY_HEAP_FRAGS;
-	factory->p        = NULL;
-	factory->hp_start = bp->mem;
-	factory->hp       = hp ? hp : bp->mem;
-	factory->hp_end   = bp->mem + bp->alloc_size;
-	factory->off_heap = &bp->off_heap;
-        factory->heap_frags = bp;
-        factory->heap_frags_saved = bp;
-        factory->alloc_type = ERTS_ALC_T_HEAP_FRAG;
-        ASSERT(!bp->next);
+    ErlHeapFragment* bp;
+    if (msgp->data.attached == ERTS_MSG_COMBINED_HFRAG) {
+	bp = &msgp->hfrag;
+	factory->heap_frags = NULL;
     }
     else {
-	factory->mode     = FACTORY_HALLOC;
-	factory->p        = rp;
-	factory->hp_start = hp;
-	factory->hp       = hp;
-	factory->hp_end   = HEAP_TOP(rp);
-	factory->off_heap = &rp->off_heap;
-        factory->heap_frags_saved = rp->mbuf;
-        factory->heap_frags = NULL; /* not used */
-        factory->alloc_type = 0; /* not used */
+	bp = msgp->data.heap_frag;
+	factory->heap_frags = bp;
     }
+    factory->mode     = FACTORY_MESSAGE;
+    factory->p        = NULL;
+    factory->hp_start = bp->mem;
+    factory->hp       = hp;
+    factory->hp_end   = bp->mem + bp->alloc_size;
+    factory->message  = msgp;
+    factory->off_heap = &bp->off_heap;
+    factory->heap_frags_saved = NULL;
+    factory->heap_frags_saved_used = 0;
+    factory->alloc_type = ERTS_ALC_T_HEAP_FRAG;
+    ASSERT(!bp->next);
     factory->off_heap_saved.first    = factory->off_heap->first;
     factory->off_heap_saved.overhead = factory->off_heap->overhead;
 
@@ -1230,8 +1511,16 @@ static void reserve_heap(ErtsHeapFactory* factory, Uint need, Uint xtra)
 	factory->hp_end = factory->hp + need;
 	return;
 
-    case FACTORY_HEAP_FRAGS:
-	bp = factory->heap_frags;
+    case FACTORY_MESSAGE:
+	if (!factory->heap_frags) {
+	    ASSERT(factory->message->data.attached == ERTS_MSG_COMBINED_HFRAG);
+	    bp = &factory->message->hfrag;
+	}
+	else {
+	    /* Fall through */
+	case FACTORY_HEAP_FRAGS:
+	    bp = factory->heap_frags;
+	}
 
         if (bp) {
 	    ASSERT(factory->hp > bp->mem);
@@ -1269,8 +1558,23 @@ void erts_factory_close(ErtsHeapFactory* factory)
 	HRelease(factory->p, factory->hp_end, factory->hp);
 	break;
 
-    case FACTORY_HEAP_FRAGS:
-	bp = factory->heap_frags;
+    case FACTORY_MESSAGE:
+	if (!factory->heap_frags) {
+	    if (factory->message->data.attached == ERTS_MSG_COMBINED_HFRAG)
+		bp = &factory->message->hfrag;
+	    else
+		bp = NULL;
+	}
+	else {
+	    if (factory->message->data.attached	== ERTS_MSG_COMBINED_HFRAG)
+		factory->message->hfrag.next = factory->heap_frags;
+	    else
+		factory->message->data.heap_frag = factory->heap_frags;
+
+	    /* Fall through */
+	case FACTORY_HEAP_FRAGS:
+	    bp = factory->heap_frags;
+	}
 
 	if (bp) {
 	    ASSERT(factory->hp >= bp->mem);
@@ -1291,17 +1595,47 @@ void erts_factory_close(ErtsHeapFactory* factory)
 void erts_factory_trim_and_close(ErtsHeapFactory* factory,
 				 Eterm *brefs, Uint brefs_size)
 {
-    if (factory->mode == FACTORY_HEAP_FRAGS) {
-        ErlHeapFragment* bp = factory->heap_frags;
+    ErlHeapFragment *bp;
+
+    switch (factory->mode) {
+    case FACTORY_MESSAGE: {
+	ErtsMessage *mp = factory->message;
+	if (mp->data.attached == ERTS_MSG_COMBINED_HFRAG) {
+	    if (!mp->hfrag.next) {
+		Uint sz = factory->hp - factory->hp_start;
+		mp = erts_shrink_message(mp, sz, brefs, brefs_size);
+		factory->message = mp;
+		factory->mode = FACTORY_CLOSED;
+		return;
+	    }
+	    /*else we don't trim multi fragmented messages for now (off_heap...) */
+	    break;
+	}
+	/* Fall through... */
+    }
+    case FACTORY_HEAP_FRAGS:
+	bp = factory->heap_frags;
+	if (!bp)
+	    break;
         if (bp->next == NULL) {
             Uint used_sz = factory->hp - bp->mem;
             ASSERT(used_sz <= bp->alloc_size);
-            factory->heap_frags = erts_resize_message_buffer(bp, used_sz,
-                                                             brefs, brefs_size);
+	    if (used_sz > 0)
+		bp = erts_resize_message_buffer(bp, used_sz,
+						brefs, brefs_size);
+	    else {
+		free_message_buffer(bp);
+		bp = NULL;
+	    }
+	    factory->heap_frags = bp;
+	    if (factory->mode == FACTORY_MESSAGE)
+		factory->message->data.heap_frag = bp;
             factory->mode = FACTORY_CLOSED;
             return;
         }
-        /*else we don't trim multi fragmented messages for now */
+        /*else we don't trim multi fragmented messages for now (off_heap...) */
+    default:
+	break;
     }
     erts_factory_close(factory);
 }
@@ -1349,38 +1683,35 @@ void erts_factory_undo(ErtsHeapFactory* factory)
 
             /* Rollback heap top
 	     */
-            if (factory->heap_frags_saved == NULL) { /* No heap frags when we started */
-                ASSERT(factory->hp_start >= HEAP_START(factory->p));
-                ASSERT(factory->hp_start <= HEAP_LIMIT(factory->p));
 
-                HEAP_TOP(factory->p) = factory->hp_start;
-            }
-            else {
+	    if (HEAP_START(factory->p) <= factory->hp_start
+		&& factory->hp_start <= HEAP_LIMIT(factory->p)) {
+		HEAP_TOP(factory->p) = factory->hp_start;
+	    }
+
+	    /* Fix last heap frag */
+            if (factory->heap_frags_saved) {
                 ASSERT(factory->heap_frags_saved == factory->p->mbuf);
-                if (factory->hp_start == factory->heap_frags_saved->mem) {
+                if (factory->hp_start != factory->heap_frags_saved->mem)
+                    factory->heap_frags_saved->used_size = factory->heap_frags_saved_used;
+		else {
                     factory->p->mbuf = factory->p->mbuf->next;
                     ERTS_HEAP_FREE(ERTS_ALC_T_HEAP_FRAG, factory->heap_frags_saved,
                                    ERTS_HEAP_FRAG_SIZE(factory->heap_frags_saved->alloc_size));
                 }
-                else if (factory->hp_start != factory->hp_end) {
-                    unsigned remains = factory->hp_start - factory->heap_frags_saved->mem;
-                    ASSERT(remains > 0 && remains < factory->heap_frags_saved->used_size);
-                    factory->heap_frags_saved->used_size = remains;
-                }
             }
         }
         break;
 
+    case FACTORY_MESSAGE:
+	if (factory->message->data.attached == ERTS_MSG_COMBINED_HFRAG)
+	    factory->message->hfrag.next = factory->heap_frags;
+	else
+	    factory->message->data.heap_frag = factory->heap_frags;
+	erts_cleanup_messages(factory->message);
+	break;
     case FACTORY_HEAP_FRAGS:
-        bp = factory->heap_frags;
-        do {
-            ErlHeapFragment* next_bp = bp->next;
-
-            erts_cleanup_offheap(&bp->off_heap);
-            ERTS_HEAP_FREE(factory->alloc_type, (void *) bp,
-                           ERTS_HEAP_FRAG_SIZE(bp->size));
-            bp = next_bp;
-        }while (bp != NULL);
+	free_message_buffer(factory->heap_frags);
 	break;
 
     case FACTORY_CLOSED: break;
diff --git a/erts/emulator/beam/erl_message.h b/erts/emulator/beam/erl_message.h
index f37b430d27..740ae46a0f 100644
--- a/erts/emulator/beam/erl_message.h
+++ b/erts/emulator/beam/erl_message.h
@@ -24,6 +24,8 @@
 struct proc_bin;
 struct external_thing_;
 
+typedef struct erl_mesg ErtsMessage;
+
 /*
  * This struct represents data that must be updated by structure copy,
  * but is stored outside of any heap.
@@ -54,6 +56,7 @@ typedef struct {
     enum {
         FACTORY_CLOSED = 0,
         FACTORY_HALLOC,
+        FACTORY_MESSAGE,
         FACTORY_HEAP_FRAGS,
         FACTORY_STATIC
     } mode;
@@ -61,8 +64,10 @@ typedef struct {
     Eterm* hp_start;
     Eterm* hp;
     Eterm* hp_end;
+    ErtsMessage *message;
     struct erl_heap_fragment* heap_frags;
     struct erl_heap_fragment* heap_frags_saved;
+    Uint heap_frags_saved_used;
     ErlOffHeap* off_heap;
     ErlOffHeap off_heap_saved;
     Uint32 alloc_type;
@@ -70,7 +75,10 @@ typedef struct {
 
 void erts_factory_proc_init(ErtsHeapFactory*, Process*);
 void erts_factory_proc_prealloc_init(ErtsHeapFactory*, Process*, Sint size);
-void erts_factory_message_init(ErtsHeapFactory*, Process*, Eterm* hp, struct erl_heap_fragment*);
+void erts_factory_heap_frag_init(ErtsHeapFactory*, struct erl_heap_fragment*);
+ErtsMessage *erts_factory_message_create(ErtsHeapFactory *, Process *,
+					  ErtsProcLocks *, Uint sz);
+void erts_factory_selfcontained_message_init(ErtsHeapFactory*, ErtsMessage *, Eterm *);
 void erts_factory_static_init(ErtsHeapFactory*, Eterm* hp, Uint size, ErlOffHeap*);
 void erts_factory_dummy_init(ErtsHeapFactory*);
 
@@ -91,6 +99,8 @@ void erts_factory_undo(ErtsHeapFactory*);
 #include "external.h"
 #include "erl_process.h"
 
+#define ERTS_INVALID_HFRAG_PTR ((ErlHeapFragment *) ~((UWord) 7))
+
 /*
  * This struct represents a heap fragment, which is used when there
  * isn't sufficient room in the process heap and we can't do a GC.
@@ -105,33 +115,46 @@ struct erl_heap_fragment {
     Eterm mem[1];		/* Data */
 };
 
-typedef struct erl_mesg {
-    struct erl_mesg* next;	/* Next message */
-    union {
-	ErtsDistExternal *dist_ext;
-	ErlHeapFragment *heap_frag;
-	void *attached;
-    } data;
-#ifdef USE_VM_PROBES
-    Eterm m[3];                 /* m[0] = message, m[1] = seq trace token, m[3] = dynamic trace user tag */
-#else
-    Eterm m[2];			/* m[0] = message, m[1] = seq trace token */
-#endif
-} ErlMessage;
-
+/* m[0] = message, m[1] = seq trace token */
+#define ERL_MESSAGE_REF_ARRAY_SZ 2
 #define ERL_MESSAGE_TERM(mp) ((mp)->m[0])
 #define ERL_MESSAGE_TOKEN(mp) ((mp)->m[1])
+
 #ifdef USE_VM_PROBES
+/* m[2] = dynamic trace user tag */
+#undef ERL_MESSAGE_REF_ARRAY_SZ
+#define ERL_MESSAGE_REF_ARRAY_SZ 3
 #define ERL_MESSAGE_DT_UTAG(mp) ((mp)->m[2])
+#else
 #endif
 
+#define ERL_MESSAGE_REF_FIELDS__			\
+    ErtsMessage *next;	/* Next message */		\
+    union {						\
+	ErtsDistExternal *dist_ext;			\
+	ErlHeapFragment *heap_frag;			\
+	void *attached;					\
+    } data;						\
+    Eterm m[ERL_MESSAGE_REF_ARRAY_SZ]
+
+
+typedef struct erl_msg_ref__ {
+    ERL_MESSAGE_REF_FIELDS__;
+} ErtsMessageRef;
+
+struct erl_mesg {
+    ERL_MESSAGE_REF_FIELDS__;
+
+    ErlHeapFragment hfrag;
+};
+
 /* Size of default message buffer (erl_message.c) */
 #define ERL_MESSAGE_BUF_SZ 500
 
 typedef struct {
-    ErlMessage* first;
-    ErlMessage** last;  /* point to the last next pointer */
-    ErlMessage** save;
+    ErtsMessage* first;
+    ErtsMessage** last;  /* point to the last next pointer */
+    ErtsMessage** save;
     Sint len;            /* queue length */
 
     /*
@@ -139,14 +162,14 @@ typedef struct {
      * recv_set/1 instructions.
      */
     BeamInstr* mark;		/* address to rec_loop/2 instruction */
-    ErlMessage** saved_last;	/* saved last pointer */
+    ErtsMessage** saved_last;	/* saved last pointer */
 } ErlMessageQueue;
 
 #ifdef ERTS_SMP
 
 typedef struct {
-    ErlMessage* first;
-    ErlMessage** last;  /* point to the last next pointer */
+    ErtsMessage* first;
+    ErtsMessage** last;  /* point to the last next pointer */
     Sint len;            /* queue length */
 } ErlMessageInQueue;
 
@@ -197,7 +220,7 @@ do {									\
 
 /* Unlink current message */
 #define UNLINK_MESSAGE(p,msgp) do { \
-     ErlMessage* __mp = (msgp)->next; \
+     ErtsMessage* __mp = (msgp)->next; \
      *(p)->msg.save = __mp; \
      (p)->msg.len--; \
      if (__mp == NULL) \
@@ -213,76 +236,33 @@ do {									\
 #define SAVE_MESSAGE(p) \
      (p)->msg.save = &(*(p)->msg.save)->next
 
-/*
- * ErtsMoveMsgAttachmentIntoProc() moves data attached to a message
- * onto the heap of a process. The attached data is the content of
- * the the message either on the internal format or on the external
- * format, and also possibly a seq trace token on the internal format.
- * If the message content is on the external format, the decode might
- * fail. If the decoding fails, ERL_MESSAGE_TERM(M) will contain
- * THE_NON_VALUE. That is, ERL_MESSAGE_TERM(M) *has* to be checked
- * afterwards and taken care of appropriately.
- *
- * ErtsMoveMsgAttachmentIntoProc() will shallow copy to heap if
- * possible; otherwise, move to heap via garbage collection.
- *
- * ErtsMoveMsgAttachmentIntoProc() is used when receiveing messages
- * in process_main() and in hipe_check_get_msg().
- */
-
-#define ErtsMoveMsgAttachmentIntoProc(M, P, ST, HT, FC, SWPO, SWPI)	\
-do {									\
-    if ((M)->data.attached) {						\
-	Uint need__ = erts_msg_attached_data_size((M));			\
-        { SWPO ; }							\
- 	if ((ST) - (HT) >= need__) {					\
-            ErtsHeapFactory factory__;                                  \
-            erts_factory_proc_prealloc_init(&factory__, (P), need__);   \
-	    erts_move_msg_attached_data_to_heap(&factory__, (M));       \
-            erts_factory_close(&factory__);                             \
-            if ((P)->mbuf != NULL) {                                    \
-                /* Heap was exhausted by messages. This is a rare case */   \
-                /* that can currently (OTP 18) only happen if hamts are */  \
-                /* far exceeding the estimated heap size. Do GC. */         \
-                (FC) -= erts_garbage_collect((P), 0, NULL, 0);		\
-            }								\
-	}								\
-	else {								\
-	    (FC) -= erts_garbage_collect((P), 0, NULL, 0);		\
-	}								\
-        { SWPI ; }							\
-	ASSERT(!(M)->data.attached);					\
-    }									\
-} while (0)
-
 #define ERTS_SND_FLG_NO_SEQ_TRACE		(((unsigned) 1) << 0)
 
 #define ERTS_HEAP_FRAG_SIZE(DATA_WORDS) \
    (sizeof(ErlHeapFragment) - sizeof(Eterm) + (DATA_WORDS)*sizeof(Eterm))
 
-#define ERTS_INIT_HEAP_FRAG(HEAP_FRAG_P, DATA_WORDS)	\
-do {							\
-    (HEAP_FRAG_P)->next = NULL;				\
-    (HEAP_FRAG_P)->alloc_size = (DATA_WORDS);		\
-    (HEAP_FRAG_P)->used_size = (DATA_WORDS);            \
-    (HEAP_FRAG_P)->off_heap.first = NULL; 	        \
-    (HEAP_FRAG_P)->off_heap.overhead = 0;		\
-} while (0)
+#define ERTS_INIT_HEAP_FRAG(HEAP_FRAG_P, USED_WORDS, DATA_WORDS)	\
+    do {								\
+	(HEAP_FRAG_P)->next = NULL;					\
+	(HEAP_FRAG_P)->alloc_size = (DATA_WORDS);			\
+	(HEAP_FRAG_P)->used_size = (USED_WORDS);			\
+	(HEAP_FRAG_P)->off_heap.first = NULL;				\
+	(HEAP_FRAG_P)->off_heap.overhead = 0;				\
+    } while (0)
 
 void init_message(void);
-void free_message(ErlMessage *);
 ErlHeapFragment* new_message_buffer(Uint);
 ErlHeapFragment* erts_resize_message_buffer(ErlHeapFragment *, Uint,
 					    Eterm *, Uint);
 void free_message_buffer(ErlHeapFragment *);
 void erts_queue_dist_message(Process*, ErtsProcLocks*, ErtsDistExternal *, Eterm);
 #ifdef USE_VM_PROBES
-void erts_queue_message_probe(Process*, ErtsProcLocks*, ErlHeapFragment*,
+void erts_queue_message_probe(Process*, ErtsProcLocks*, ErtsMessage*,
                               Eterm message, Eterm seq_trace_token, Eterm dt_utag);
 #define erts_queue_message(RP,RL,BP,Msg,SEQ) \
     erts_queue_message_probe((RP),(RL),(BP),(Msg),(SEQ),NIL)
 #else
-void erts_queue_message(Process*, ErtsProcLocks*, ErlHeapFragment*,
+void erts_queue_message(Process*, ErtsProcLocks*, ErtsMessage*,
                         Eterm message, Eterm seq_trace_token);
 #define erts_queue_message_probe(RP,RL,BP,Msg,SEQ,TAG) \
     erts_queue_message((RP),(RL),(BP),(Msg),(SEQ))
@@ -291,20 +271,141 @@ void erts_deliver_exit_message(Eterm, Process*, ErtsProcLocks *, Eterm, Eterm);
 Sint erts_send_message(Process*, Process*, ErtsProcLocks*, Eterm, unsigned);
 void erts_link_mbuf_to_proc(Process *proc, ErlHeapFragment *bp);
 
-void erts_move_msg_mbuf_to_heap(Eterm**, ErlOffHeap*, ErlMessage *);
-
-Uint erts_msg_attached_data_size_aux(ErlMessage *msg);
-void erts_move_msg_attached_data_to_heap(ErtsHeapFactory*, ErlMessage *);
-Eterm erts_msg_distext2heap(Process *, ErtsProcLocks *, ErlHeapFragment **,
-			    Eterm *, ErtsDistExternal *);
+Uint erts_msg_attached_data_size_aux(ErtsMessage *msg);
 
 void erts_cleanup_offheap(ErlOffHeap *offheap);
+void erts_save_message_in_proc(Process *p, ErtsMessage *msg);
+Sint erts_move_messages_off_heap(Process *c_p);
+Sint erts_complete_off_heap_message_queue_change(Process *c_p);
+Eterm erts_change_off_heap_message_queue_state(Process *c_p, int enable);
+
+int erts_decode_dist_message(Process *, ErtsProcLocks, ErtsMessage *, int);
+
+void erts_cleanup_messages(ErtsMessage *mp);
+
+typedef struct {
+    Uint size;
+    ErtsMessage *msgp;
+} ErtsMessageInfo;
+
+Uint erts_prep_msgq_for_inspection(Process *c_p,
+				   Process *rp,
+				   ErtsProcLocks rp_locks,
+				   ErtsMessageInfo *mip);
 
+void *erts_alloc_message_ref(void);
+void erts_free_message_ref(void *);
 
+#define ERTS_SMALL_FIX_MSG_SZ 10
+#define ERTS_MEDIUM_FIX_MSG_SZ 20
+#define ERTS_LARGE_FIX_MSG_SZ 30
+
+void *erts_alloc_small_message(void);
+void erts_free_small_message(void *mp);
+
+typedef struct {
+    ErtsMessage m;
+    Eterm data[ERTS_SMALL_FIX_MSG_SZ-1];
+} ErtsSmallFixSzMessage;
+
+typedef struct {
+    ErtsMessage m;
+    Eterm data[ERTS_MEDIUM_FIX_MSG_SZ-1];
+} ErtsMediumFixSzMessage;
+
+typedef struct {
+    ErtsMessage m;
+    Eterm data[ERTS_LARGE_FIX_MSG_SZ-1];
+} ErtsLargeFixSzMessage;
+
+ErtsMessage *erts_try_alloc_message_on_heap(Process *pp,
+					    erts_aint32_t *psp,
+					    ErtsProcLocks *plp,
+					    Uint sz,
+					    Eterm **hpp,
+					    ErlOffHeap **ohpp,
+					    int *on_heap_p);
+ErtsMessage *erts_realloc_shrink_message(ErtsMessage *mp, Uint sz,
+					 Eterm *brefs, Uint brefs_size);
+
+ERTS_GLB_FORCE_INLINE ErtsMessage *erts_alloc_message(Uint sz, Eterm **hpp);
+ERTS_GLB_FORCE_INLINE ErtsMessage *erts_shrink_message(ErtsMessage *mp, Uint sz,
+						       Eterm *brefs, Uint brefs_size);
+ERTS_GLB_FORCE_INLINE void erts_free_message(ErtsMessage *mp);
 ERTS_GLB_INLINE Uint erts_used_frag_sz(const ErlHeapFragment*);
-ERTS_GLB_INLINE Uint erts_msg_attached_data_size(ErlMessage *msg);
+ERTS_GLB_INLINE Uint erts_msg_attached_data_size(ErtsMessage *msg);
+
+#define ERTS_MSG_COMBINED_HFRAG ((void *) 0x1)
 
 #if ERTS_GLB_INLINE_INCL_FUNC_DEF
+
+ERTS_GLB_FORCE_INLINE ErtsMessage *erts_alloc_message(Uint sz, Eterm **hpp)
+{
+    ErtsMessage *mp;
+
+    if (sz == 0) {
+	mp = erts_alloc_message_ref();
+	mp->next = NULL;
+	ERL_MESSAGE_TERM(mp) = NIL;
+	mp->data.attached = NULL;
+	if (hpp)
+	    *hpp = NULL;
+	return mp;
+    }
+
+    mp = erts_alloc(ERTS_ALC_T_MSG,
+		    sizeof(ErtsMessage) + (sz - 1)*sizeof(Eterm));
+
+    mp->next = NULL;
+    ERL_MESSAGE_TERM(mp) = NIL;
+    mp->data.attached = ERTS_MSG_COMBINED_HFRAG;
+    ERTS_INIT_HEAP_FRAG(&mp->hfrag, sz, sz);
+
+    if (hpp)
+	*hpp = &mp->hfrag.mem[0];
+
+    return mp;
+}
+
+ERTS_GLB_FORCE_INLINE ErtsMessage *
+erts_shrink_message(ErtsMessage *mp, Uint sz, Eterm *brefs, Uint brefs_size)
+{
+    if (sz == 0) {
+	ErtsMessage *nmp;
+	if (!mp->data.attached)
+	    return mp;
+	ASSERT(mp->data.attached == ERTS_MSG_COMBINED_HFRAG);
+	nmp = erts_alloc_message_ref();
+#ifdef DEBUG
+	if (brefs && brefs_size) {
+	    int i;
+	    for (i = 0; i < brefs_size; i++)
+		ASSERT(is_non_value(brefs[i]) || is_immed(brefs[i]));
+	}
+#endif
+	erts_free(ERTS_ALC_T_MSG, mp);
+	return nmp;
+    }
+
+    ASSERT(mp->data.attached == ERTS_MSG_COMBINED_HFRAG);
+    ASSERT(mp->hfrag.used_size >= sz);
+
+    if (sz >= (mp->hfrag.alloc_size - mp->hfrag.alloc_size / 16)) {
+	mp->hfrag.used_size = sz;
+	return mp;
+    }
+
+    return erts_realloc_shrink_message(mp, sz, brefs, brefs_size);
+}
+
+ERTS_GLB_FORCE_INLINE void erts_free_message(ErtsMessage *mp)
+{
+    if (mp->data.attached != ERTS_MSG_COMBINED_HFRAG)
+	erts_free_message_ref(mp);
+    else
+	erts_free(ERTS_ALC_T_MSG, mp);
+}
+
 ERTS_GLB_INLINE Uint erts_used_frag_sz(const ErlHeapFragment* bp)
 {
     Uint sz = 0;
@@ -314,11 +415,17 @@ ERTS_GLB_INLINE Uint erts_used_frag_sz(const ErlHeapFragment* bp)
     return sz;
 }
 
-ERTS_GLB_INLINE Uint erts_msg_attached_data_size(ErlMessage *msg)
+ERTS_GLB_INLINE Uint erts_msg_attached_data_size(ErtsMessage *msg)
 {
     ASSERT(msg->data.attached);
-    if (is_value(ERL_MESSAGE_TERM(msg)))
-	return erts_used_frag_sz(msg->data.heap_frag);
+    if (is_value(ERL_MESSAGE_TERM(msg))) {
+	ErlHeapFragment *bp;
+	if (msg->data.attached == ERTS_MSG_COMBINED_HFRAG)
+	    bp = &msg->hfrag;
+	else
+	    bp = msg->data.heap_frag;
+	return erts_used_frag_sz(bp);
+    }
     else if (msg->data.dist_ext->heap_size < 0)
 	return erts_msg_attached_data_size_aux(msg);
     else {
diff --git a/erts/emulator/beam/erl_nif.c b/erts/emulator/beam/erl_nif.c
index 01414f326d..a37cda93ef 100644
--- a/erts/emulator/beam/erl_nif.c
+++ b/erts/emulator/beam/erl_nif.c
@@ -314,6 +314,7 @@ int enif_send(ErlNifEnv* env, const ErlNifPid* to_pid,
     ErtsProcLocks rp_locks = 0;
     Process* rp;
     Process* c_p;
+    ErtsMessage *mp;
     ErlHeapFragment* frags;
     Eterm receiver = to_pid->pid;
     int flush_me = 0;
@@ -347,7 +348,7 @@ int enif_send(ErlNifEnv* env, const ErlNifPid* to_pid,
     ASSERT(frags == MBUF(&menv->phony_proc));
     if (frags != NULL) {
 	/* Move all offheap's from phony proc to the first fragment.
-	   Quick and dirty, but erts_move_msg_mbuf_to_heap doesn't care. */
+	   Quick and dirty... */
 	ASSERT(!is_offheap(&frags->off_heap));
 	frags->off_heap = MSO(&menv->phony_proc);
 	clear_offheap(&MSO(&menv->phony_proc));
@@ -359,7 +360,9 @@ int enif_send(ErlNifEnv* env, const ErlNifPid* to_pid,
     if (flush_me) {	
 	flush_env(env); /* Needed for ERTS_HOLE_CHECK */ 
     }
-    erts_queue_message(rp, &rp_locks, frags, msg, am_undefined);
+    mp = erts_alloc_message(0, NULL);
+    mp->data.heap_frag = frags;
+    erts_queue_message(rp, &rp_locks, mp, msg, am_undefined);
     if (c_p == rp)
 	rp_locks &= ~ERTS_PROC_LOCK_MAIN;
     if (rp_locks)
diff --git a/erts/emulator/beam/erl_node_tables.c b/erts/emulator/beam/erl_node_tables.c
index 62a44f7129..a4da288e79 100644
--- a/erts/emulator/beam/erl_node_tables.c
+++ b/erts/emulator/beam/erl_node_tables.c
@@ -1401,56 +1401,50 @@ setup_reference_table(void)
     for (i = 0; i < max; i++) {
 	Process *proc = erts_pix2proc(i);
 	if (proc) {
-	    ErlMessage *msg;
+	    int mli;
+	    ErtsMessage *msg_list[] = {
+		proc->msg.first,
+#ifdef ERTS_SMP
+		proc->msg_inq.first,
+#endif
+		proc->msg_frag};
 
 	    /* Insert Heap */
 	    insert_offheap(&(proc->off_heap),
 			   HEAP_REF,
 			   proc->common.id);
-	    /* Insert message buffers */
+	    /* Insert heap fragments buffers */
 	    for(hfp = proc->mbuf; hfp; hfp = hfp->next)
 		insert_offheap(&(hfp->off_heap),
 			       HEAP_REF,
 			       proc->common.id);
-	    /* Insert msg msg buffers */
-	    for (msg = proc->msg.first; msg; msg = msg->next) {
-		ErlHeapFragment *heap_frag = NULL;
-		if (msg->data.attached) {
-		    if (is_value(ERL_MESSAGE_TERM(msg)))
-			heap_frag = msg->data.heap_frag;
-		    else {
-			if (msg->data.dist_ext->dep)
-			    insert_dist_entry(msg->data.dist_ext->dep,
-					      HEAP_REF, proc->common.id, 0);
-			if (is_not_nil(ERL_MESSAGE_TOKEN(msg)))
-			    heap_frag = erts_dist_ext_trailer(msg->data.dist_ext);
+
+	    /* Insert msg buffers */
+	    for (mli = 0; mli < sizeof(msg_list)/sizeof(msg_list[0]); mli++) {
+		ErtsMessage *msg;
+		for (msg = msg_list[mli]; msg; msg = msg->next) {
+		    ErlHeapFragment *heap_frag = NULL;
+		    if (msg->data.attached) {
+			if (msg->data.attached == ERTS_MSG_COMBINED_HFRAG)
+			    heap_frag = &msg->hfrag;
+			else if (is_value(ERL_MESSAGE_TERM(msg)))
+			    heap_frag = msg->data.heap_frag;
+			else {
+			    if (msg->data.dist_ext->dep)
+				insert_dist_entry(msg->data.dist_ext->dep,
+						  HEAP_REF, proc->common.id, 0);
+			    if (is_not_nil(ERL_MESSAGE_TOKEN(msg)))
+				heap_frag = erts_dist_ext_trailer(msg->data.dist_ext);
+			}
 		    }
-		}
-		if (heap_frag)
-		    insert_offheap(&(heap_frag->off_heap),
-				   HEAP_REF,
-				   proc->common.id);
-	    }
-#ifdef ERTS_SMP
-	    for (msg = proc->msg_inq.first; msg; msg = msg->next) {
-		ErlHeapFragment *heap_frag = NULL;
-		if (msg->data.attached) {
-		    if (is_value(ERL_MESSAGE_TERM(msg)))
-			heap_frag = msg->data.heap_frag;
-		    else {
-			if (msg->data.dist_ext->dep)
-			    insert_dist_entry(msg->data.dist_ext->dep,
-					      HEAP_REF, proc->common.id, 0);
-			if (is_not_nil(ERL_MESSAGE_TOKEN(msg)))
-			    heap_frag = erts_dist_ext_trailer(msg->data.dist_ext);
+		    while (heap_frag) {
+			insert_offheap(&(heap_frag->off_heap),
+				       HEAP_REF,
+				       proc->common.id);
+			heap_frag = heap_frag->next;
 		    }
 		}
-		if (heap_frag)
-		    insert_offheap(&(heap_frag->off_heap),
-				   HEAP_REF,
-				   proc->common.id);
 	    }
-#endif
 	    /* Insert links */
 	    if (ERTS_P_LINKS(proc))
 		insert_links(ERTS_P_LINKS(proc), proc->common.id);
diff --git a/erts/emulator/beam/erl_process.c b/erts/emulator/beam/erl_process.c
index 15a6d5d651..6e83456e4c 100644
--- a/erts/emulator/beam/erl_process.c
+++ b/erts/emulator/beam/erl_process.c
@@ -148,6 +148,7 @@ extern BeamInstr beam_apply[];
 extern BeamInstr beam_exit[];
 extern BeamInstr beam_continue_exit[];
 
+int erts_default_spo_flags = 0;
 int erts_eager_check_io = 1;
 int erts_sched_compact_load;
 int erts_sched_balance_util = 0;
@@ -351,7 +352,8 @@ struct erts_system_profile_flags_t erts_system_profile_flags;
 
 typedef enum {
     ERTS_PSTT_GC,	/* Garbage Collect */
-    ERTS_PSTT_CPC	/* Check Process Code */
+    ERTS_PSTT_CPC,	/* Check Process Code */
+    ERTS_PSTT_COHMQ     /* Change off heap message queue */
 } ErtsProcSysTaskType;
 
 #define ERTS_MAX_PROC_SYS_TASK_ARGS 2
@@ -982,7 +984,7 @@ reply_sched_wall_time(void *vswtrp)
     Eterm **hpp;
     Uint sz, *szp;
     ErlOffHeap *ohp = NULL;
-    ErlHeapFragment *bp = NULL;
+    ErtsMessage *mp = NULL;
 
     ASSERT(esdp);
 #ifdef ERTS_DIRTY_SCHEDULERS
@@ -1038,12 +1040,12 @@ reply_sched_wall_time(void *vswtrp)
 	if (hpp)
 	    break;
 
-	hp = erts_alloc_message_heap(sz, &bp, &ohp, rp, &rp_locks);
+	mp = erts_alloc_message_heap(rp, &rp_locks, sz, &hp, &ohp);
 	szp = NULL;
 	hpp = &hp;
     }
 
-    erts_queue_message(rp, &rp_locks, bp, msg, NIL);
+    erts_queue_message(rp, &rp_locks, mp, msg, NIL);
 
     if (swtrp->req_sched == esdp->no)
 	rp_locks &= ~ERTS_PROC_LOCK_MAIN;
@@ -6294,22 +6296,99 @@ erts_schedule_process(Process *p, erts_aint32_t state, ErtsProcLocks locks)
     schedule_process(p, state, locks);
 }
 
-static void
-schedule_process_sys_task(Process *p, erts_aint32_t state, Process *proxy)
+static int
+schedule_process_sys_task(Process *p, erts_aint32_t prio, ErtsProcSysTask *st)
 {
-    /*
-     * Expects status lock to be locked when called, and
-     * returns with status lock unlocked...
-     */
-    erts_aint32_t a = state, n, enq_prio = -1;
+    int res;
+    int locked;
+    ErtsProcSysTaskQs *stqs, *free_stqs;
+    erts_aint32_t state, a, n, enq_prio;
     int enqueue; /* < 0 -> use proxy */
-    unsigned int prof_runnable_procs = erts_system_profile_flags.runnable_procs;
+    unsigned int prof_runnable_procs;
+
+    res = 1; /* prepare for success */
+    st->next = st->prev = st; /* Prep for empty prio queue */
+    state = erts_smp_atomic32_read_nob(&p->state);
+    prof_runnable_procs = erts_system_profile_flags.runnable_procs;
+    locked = 0;
+    free_stqs = NULL;
+    if (state & ERTS_PSFLG_ACTIVE_SYS)
+	stqs = NULL;
+    else {
+    alloc_qs:
+	stqs = proc_sys_task_queues_alloc();
+	stqs->qmask = 1 << prio;
+	stqs->ncount = 0;
+	stqs->q[PRIORITY_MAX] = NULL;
+	stqs->q[PRIORITY_HIGH] = NULL;
+	stqs->q[PRIORITY_NORMAL] = NULL;
+	stqs->q[PRIORITY_LOW] = NULL;
+	stqs->q[prio] = st;
+    }
+
+    if (!locked) {
+	locked = 1;
+	erts_smp_proc_lock(p, ERTS_PROC_LOCK_STATUS);
+
+	state = erts_smp_atomic32_read_nob(&p->state);
+	if (state & ERTS_PSFLG_EXITING) {
+	    free_stqs = stqs;
+	    res = 0;
+	    goto cleanup;
+	}
+    }
+
+    if (!p->sys_task_qs) {
+	if (stqs)
+	    p->sys_task_qs = stqs;
+	else
+	    goto alloc_qs;
+    }
+    else {
+	free_stqs = stqs;
+	stqs = p->sys_task_qs;
+	if (!stqs->q[prio]) {
+	    stqs->q[prio] = st;
+	    stqs->qmask |= 1 << prio;
+	}
+	else {
+	    st->next = stqs->q[prio];
+	    st->prev = stqs->q[prio]->prev;
+	    st->next->prev = st;
+	    st->prev->next = st;
+	    ASSERT(stqs->qmask & (1 << prio));
+	}
+    }
+
+    if (ERTS_PSFLGS_GET_ACT_PRIO(state) > prio) {
+	erts_aint32_t n, a, e;
+	/* Need to elevate actual prio */
+
+	a = state;
+	do {
+	    if (ERTS_PSFLGS_GET_ACT_PRIO(a) <= prio) {
+		n = a;
+		break;
+	    }
+	    n = e = a;
+	    n &= ~ERTS_PSFLGS_ACT_PRIO_MASK;
+	    n |= (prio << ERTS_PSFLGS_ACT_PRIO_OFFSET);
+	    a = erts_smp_atomic32_cmpxchg_nob(&p->state, n, e);    
+	} while (a != e);
+	state = n;
+    }
+
+
+    a = state;
+    enq_prio = -1;
 
     /* Status lock prevents out of order "runnable proc" trace msgs */
     ERTS_SMP_LC_ASSERT(ERTS_PROC_LOCK_STATUS & erts_proc_lc_my_proc_locks(p));
 
-    if (!prof_runnable_procs)
+    if (!prof_runnable_procs) {
 	erts_smp_proc_unlock(p, ERTS_PROC_LOCK_STATUS);
+	locked = 0;
+    }
 
     ASSERT(!(state & ERTS_PSFLG_PROXY));
 
@@ -6317,8 +6396,10 @@ schedule_process_sys_task(Process *p, erts_aint32_t state, Process *proxy)
 	erts_aint32_t e;
 	n = e = a;
 
-	if (a & ERTS_PSFLG_FREE)
+	if (a & ERTS_PSFLG_FREE) {
+	    res = 0;
 	    goto cleanup; /* We don't want to schedule free processes... */
+	}
 
 	enqueue = ERTS_ENQUEUE_NOT;
 	n |= ERTS_PSFLG_ACTIVE_SYS;
@@ -6342,29 +6423,24 @@ schedule_process_sys_task(Process *p, erts_aint32_t state, Process *proxy)
 	}
 
 	erts_smp_proc_unlock(p, ERTS_PROC_LOCK_STATUS);
-	prof_runnable_procs = 0;
+	locked = 0;
     }
 
-    if (enqueue != ERTS_ENQUEUE_NOT) {
-	Process *sched_p;
-	if (enqueue > 0)
-	    sched_p = p;
-	else {
-	    sched_p = make_proxy_proc(proxy, p, enq_prio);
-	    proxy = NULL;
-	}
-	add2runq(sched_p, n, enq_prio);
-    }
+    if (enqueue != ERTS_ENQUEUE_NOT)
+	add2runq(enqueue > 0 ? p : make_proxy_proc(NULL, p, enq_prio),
+		 n, enq_prio);
 
 cleanup:
 
-    if (prof_runnable_procs)
+    if (locked)
 	erts_smp_proc_unlock(p, ERTS_PROC_LOCK_STATUS);
 
-    if (proxy)
-	free_proxy_proc(proxy);
+    if (free_stqs)
+	proc_sys_task_queues_free(free_stqs);
 
     ERTS_SMP_LC_ASSERT(!(ERTS_PROC_LOCK_STATUS & erts_proc_lc_my_proc_locks(p)));
+
+    return res;
 }
 
 static ERTS_INLINE int
@@ -9701,13 +9777,13 @@ Process *schedule(Process *p, int calls)
 	    }
 	}
 
-	if (!(state & ERTS_PSFLG_EXITING)
-	    && ((FLAGS(p) & F_FORCE_GC)
-		|| (MSO(p).overhead > BIN_VHEAP_SZ(p)))) {
-	    reds -= erts_garbage_collect(p, 0, p->arg_reg, p->arity);
-	    if (reds <= 0) {
-		p->fcalls = reds;
-		goto sched_out_proc;
+	if (ERTS_IS_GC_DESIRED(p)) {
+	    if (!(state & ERTS_PSFLG_EXITING) && !(p->flags & F_DISABLE_GC)) {
+		reds -= erts_garbage_collect(p, 0, p->arg_reg, p->arity);
+		if (reds <= 0) {
+		    p->fcalls = reds;
+		    goto sched_out_proc;
+		}
 	    }
 	}
 
@@ -9747,7 +9823,7 @@ notify_sys_task_executed(Process *c_p, ErtsProcSysTask *st, Eterm st_result)
     if (rp) {
 	ErtsProcLocks rp_locks;
 	ErlOffHeap *ohp;
-	ErlHeapFragment* bp;
+	ErtsMessage *mp;
 	Eterm *hp, msg, req_id, result;
 	Uint st_result_sz, hsz;
 #ifdef DEBUG
@@ -9759,11 +9835,7 @@ notify_sys_task_executed(Process *c_p, ErtsProcSysTask *st, Eterm st_result)
 	st_result_sz = is_immed(st_result) ? 0 : size_object(st_result);
 	hsz = st->req_id_sz + st_result_sz + 4 /* 3-tuple */;
 
-	hp = erts_alloc_message_heap(hsz,
-				     &bp,
-				     &ohp,
-				     rp,
-				     &rp_locks);
+	mp = erts_alloc_message_heap(rp, &rp_locks, hsz, &hp, &ohp);
 
 #ifdef DEBUG
 	hp_start = hp;
@@ -9788,7 +9860,7 @@ notify_sys_task_executed(Process *c_p, ErtsProcSysTask *st, Eterm st_result)
 	ASSERT(hp_start + hsz == hp);
 #endif
 
-	erts_queue_message(rp, &rp_locks, bp, msg, NIL);
+	erts_queue_message(rp, &rp_locks, mp, msg, NIL);
 
 	if (c_p == rp)
 	    rp_locks &= ~ERTS_PROC_LOCK_MAIN;
@@ -10010,6 +10082,10 @@ execute_sys_tasks(Process *c_p, erts_aint32_t *statep, int in_reds)
 		st = NULL;
 	    }
 	    break;
+	case ERTS_PSTT_COHMQ:
+	    reds += erts_complete_off_heap_message_queue_change(c_p);
+	    st_res = am_true;
+	    break;
 	default:
 	    ERTS_INTERNAL_ERROR("Invalid process sys task type");
 	    st_res = am_false;
@@ -10052,6 +10128,9 @@ cleanup_sys_tasks(Process *c_p, erts_aint32_t in_state, int in_reds)
 	case ERTS_PSTT_CPC:
 	    st_res = am_false;
 	    break;
+	case ERTS_PSTT_COHMQ:
+	    st_res = am_false;
+	    break;
 	default:
 	    ERTS_INTERNAL_ERROR("Invalid process sys task type");
 	    st_res = am_false;
@@ -10070,10 +10149,8 @@ BIF_RETTYPE
 erts_internal_request_system_task_3(BIF_ALIST_3)
 {
     Process *rp = erts_proc_lookup(BIF_ARG_1);
-    ErtsProcSysTaskQs *stqs, *free_stqs = NULL;
     ErtsProcSysTask *st = NULL;
-    erts_aint32_t prio, rp_state;
-    int rp_locked;
+    erts_aint32_t prio;
     Eterm noproc_res, req_type;
 
     if (!rp && !is_internal_pid(BIF_ARG_1)) {
@@ -10130,7 +10207,6 @@ erts_internal_request_system_task_3(BIF_ALIST_3)
 	}
 	st = erts_alloc(ERTS_ALC_T_PROC_SYS_TSK,
 			ERTS_PROC_SYS_TASK_SIZE(tot_sz));
-	st->next = st->prev = st; /* Prep for empty prio queue */
 	ERTS_INIT_OFF_HEAP(&st->off_heap);
 	hp = &st->heap[0];
 
@@ -10174,95 +10250,11 @@ erts_internal_request_system_task_3(BIF_ALIST_3)
 	goto badarg;
     }
 
-    rp_state = erts_smp_atomic32_read_nob(&rp->state);
-
-    rp_locked = 0;
-
-    free_stqs = NULL;
-    if (rp_state & ERTS_PSFLG_ACTIVE_SYS)
-	stqs = NULL;
-    else {
-    alloc_qs:
-	stqs = proc_sys_task_queues_alloc();
-	stqs->qmask = 1 << prio;
-	stqs->ncount = 0;
-	stqs->q[PRIORITY_MAX] = NULL;
-	stqs->q[PRIORITY_HIGH] = NULL;
-	stqs->q[PRIORITY_NORMAL] = NULL;
-	stqs->q[PRIORITY_LOW] = NULL;
-	stqs->q[prio] = st;
-    }
-
-    if (!rp_locked) {
-	rp_locked = 1;
-	erts_smp_proc_lock(rp, ERTS_PROC_LOCK_STATUS);
-
-	rp_state = erts_smp_atomic32_read_nob(&rp->state);
-	if (rp_state & ERTS_PSFLG_EXITING) {
-	    erts_smp_proc_unlock(rp, ERTS_PROC_LOCK_STATUS);
-	    rp = NULL;
-	    free_stqs = stqs;
-	    goto noproc;
-	}
+    if (!schedule_process_sys_task(rp, prio, st)) {
+    noproc:
+	notify_sys_task_executed(BIF_P, st, noproc_res);
     }
 
-    if (!rp->sys_task_qs) {
-	if (stqs)
-	    rp->sys_task_qs = stqs;
-	else
-	    goto alloc_qs;
-    }
-    else {
-	if (stqs)
-	    free_stqs = stqs;
-	stqs = rp->sys_task_qs;
-	if (!stqs->q[prio]) {
-	    stqs->q[prio] = st;
-	    stqs->qmask |= 1 << prio;
-	}
-	else {
-	    st->next = stqs->q[prio];
-	    st->prev = stqs->q[prio]->prev;
-	    st->next->prev = st;
-	    st->prev->next = st;
-	    ASSERT(stqs->qmask & (1 << prio));
-	}
-    }
-
-    if (ERTS_PSFLGS_GET_ACT_PRIO(rp_state) > prio) {
-	erts_aint32_t n, a, e;
-	/* Need to elevate actual prio */
-
-	a = rp_state;
-	do {
-	    if (ERTS_PSFLGS_GET_ACT_PRIO(a) <= prio) {
-		n = a;
-		break;
-	    }
-	    n = e = a;
-	    n &= ~ERTS_PSFLGS_ACT_PRIO_MASK;
-	    n |= (prio << ERTS_PSFLGS_ACT_PRIO_OFFSET);
-	    a = erts_smp_atomic32_cmpxchg_nob(&rp->state, n, e);    
-	} while (a != e);
-	rp_state = n;
-    }
-
-    /*
-     * schedule_process_sys_task() unlocks status
-     * lock on process.
-     */
-    schedule_process_sys_task(rp, rp_state, NULL);
-
-    if (free_stqs)
-	proc_sys_task_queues_free(free_stqs);
-
-    BIF_RET(am_ok);
-
-noproc:
-
-    notify_sys_task_executed(BIF_P, st, noproc_res);
-    if (free_stqs)
-	proc_sys_task_queues_free(free_stqs);
     BIF_RET(am_ok);
 
 badarg:
@@ -10271,11 +10263,35 @@ badarg:
 	erts_cleanup_offheap(&st->off_heap);
 	erts_free(ERTS_ALC_T_PROC_SYS_TSK, st);
     }
-    if (free_stqs)
-	proc_sys_task_queues_free(free_stqs);
     BIF_ERROR(BIF_P, BADARG);
 }
 
+void
+erts_schedule_complete_off_heap_message_queue_change(Eterm pid)
+{
+    Process *rp = erts_proc_lookup(pid);
+    if (rp) {
+	ErtsProcSysTask *st;
+	erts_aint32_t state;
+	int i;
+
+	st = erts_alloc(ERTS_ALC_T_PROC_SYS_TSK,
+			ERTS_PROC_SYS_TASK_SIZE(0));
+	st->type = ERTS_PSTT_COHMQ;
+	st->requester = NIL;
+	st->reply_tag = NIL;
+	st->req_id = NIL;
+	st->req_id_sz = 0;
+	for (i = 0; i < ERTS_MAX_PROC_SYS_TASK_ARGS; i++)
+	    st->arg[i] = NIL;
+	ERTS_INIT_OFF_HEAP(&st->off_heap);
+	state = erts_smp_atomic32_read_nob(&rp->state);
+
+	if (!schedule_process_sys_task(rp, ERTS_PSFLGS_GET_USR_PRIO(state), st))
+	    erts_free(ERTS_ALC_T_PROC_SYS_TSK, st);
+    }
+}
+
 static void
 save_gc_task(Process *c_p, ErtsProcSysTask *st, int prio)
 {
@@ -10721,6 +10737,7 @@ erl_create_process(Process* parent, /* Parent of process (default group leader).
 		   Eterm args,	/* Arguments for function (must be well-formed list). */
 		   ErlSpawnOpts* so) /* Options for spawn. */
 {
+    Uint flags = erts_default_process_flags;
     ErtsRunQueue *rq = NULL;
     Process *p;
     Sint arity;			/* Number of arguments. */
@@ -10758,6 +10775,11 @@ erl_create_process(Process* parent, /* Parent of process (default group leader).
     state |= (((prio & ERTS_PSFLGS_PRIO_MASK) << ERTS_PSFLGS_ACT_PRIO_OFFSET)
 	      | ((prio & ERTS_PSFLGS_PRIO_MASK) << ERTS_PSFLGS_USR_PRIO_OFFSET));
 
+    if (so->flags & SPO_OFF_HEAP_MSGQ) {
+	state |= ERTS_PSFLG_OFF_HEAP_MSGQ;
+	flags |= F_OFF_HEAP_MSGQ;
+    }
+
     if (!rq)
 	rq = erts_get_runq_proc(parent);
 
@@ -10780,7 +10802,7 @@ erl_create_process(Process* parent, /* Parent of process (default group leader).
     BM_SWAP_TIMER(size,system);
     heap_need = arg_size;
 
-    p->flags = erts_default_process_flags;
+    p->flags = flags;
 
     p->static_flags = 0;
     if (so->flags & SPO_SYSTEM_PROC)
@@ -10829,6 +10851,8 @@ erl_create_process(Process* parent, /* Parent of process (default group leader).
     p->stop = p->hend = p->heap + sz;
     p->htop = p->heap;
     p->heap_sz = sz;
+    p->abandoned_heap = NULL;
+    p->live_hf_end = ERTS_INVALID_HFRAG_PTR;
     p->catches = 0;
 
     p->bin_vheap_sz     = p->min_vheap_size;
@@ -10898,6 +10922,7 @@ erl_create_process(Process* parent, /* Parent of process (default group leader).
     p->accessor_bif_timers = NULL;
 #endif
     p->mbuf = NULL;
+    p->msg_frag = NULL;
     p->mbuf_sz = 0;
     p->psd = NULL;
     p->dictionary = NULL;
@@ -11033,6 +11058,8 @@ void erts_init_empty_process(Process *p)
     p->stop = NULL;
     p->hend = NULL;
     p->heap = NULL;
+    p->abandoned_heap = NULL;
+    p->live_hf_end = ERTS_INVALID_HFRAG_PTR;
     p->gen_gcs = 0;
     p->max_gen_gcs = 0;
     p->min_heap_size = 0;
@@ -11064,6 +11091,7 @@ void erts_init_empty_process(Process *p)
     p->old_htop = NULL;
     p->old_heap = NULL;
     p->mbuf = NULL;
+    p->msg_frag = NULL;
     p->mbuf_sz = 0;
     p->psd = NULL;
     ERTS_P_MONITORS(p) = NULL;
@@ -11152,6 +11180,8 @@ erts_debug_verify_clean_empty_process(Process* p)
     ASSERT(p->htop == NULL);
     ASSERT(p->stop == NULL);
     ASSERT(p->hend == NULL);
+    ASSERT(p->abandoned_heap == NULL);
+    ASSERT(p->live_hf_end == ERTS_INVALID_HFRAG_PTR);
     ASSERT(p->heap == NULL);
     ASSERT(p->common.id == ERTS_INVALID_PID);
     ASSERT(ERTS_TRACER_PROC(p) == NIL);
@@ -11229,8 +11259,6 @@ erts_cleanup_empty_process(Process* p)
 static void
 delete_process(Process* p)
 {
-    ErlMessage* mp;
-
     VERBOSE(DEBUG_PROCESSES, ("Removing process: %T\n",p->common.id));
 
     /* Cleanup psd */
@@ -11286,24 +11314,8 @@ delete_process(Process* p)
     erts_erase_dicts(p);
 
     /* free all pending messages */
-    mp = p->msg.first;
-    while(mp != NULL) {
-	ErlMessage* next_mp = mp->next;
-	if (mp->data.attached) {
-	    if (is_value(mp->m[0]))
-		free_message_buffer(mp->data.heap_frag);
-	    else {
-		if (is_not_nil(mp->m[1])) {
-		    ErlHeapFragment *heap_frag;
-		    heap_frag = (ErlHeapFragment *) mp->data.dist_ext->ext_endp;
-		    erts_cleanup_offheap(&heap_frag->off_heap);
-		}
-		erts_free_dist_ext_copy(mp->data.dist_ext);
-	    }
-	}
-	free_message(mp);
-	mp = next_mp;
-    }
+    erts_cleanup_messages(p->msg.first);
+    p->msg.first = NULL;
 
     ASSERT(!p->nodes_monitors);
     ASSERT(!p->suspend_monitors);
@@ -11491,6 +11503,9 @@ static ERTS_INLINE void
 send_exit_message(Process *to, ErtsProcLocks *to_locksp,
 		  Eterm exit_term, Uint term_size, Eterm token)
 {
+    ErtsMessage *mp;
+    ErlOffHeap *ohp;
+
     if (token == NIL 
 #ifdef USE_VM_PROBES
 	|| token == am_have_dt_utag
@@ -11498,14 +11513,12 @@ send_exit_message(Process *to, ErtsProcLocks *to_locksp,
 	) {
 	Eterm* hp;
 	Eterm mess;
-	ErlHeapFragment* bp;
-	ErlOffHeap *ohp;
 
-	hp = erts_alloc_message_heap(term_size, &bp, &ohp, to, to_locksp);
+	mp = erts_alloc_message_heap(to, to_locksp,
+				     term_size, &hp, &ohp);
 	mess = copy_struct(exit_term, term_size, &hp, ohp);
-	erts_queue_message(to, to_locksp, bp, mess, NIL);
+	erts_queue_message(to, to_locksp, mp, mess, NIL);
     } else {
-	ErlHeapFragment* bp;
 	Eterm* hp;
 	Eterm mess;
 	Eterm temp_token;
@@ -11513,13 +11526,14 @@ send_exit_message(Process *to, ErtsProcLocks *to_locksp,
 
 	ASSERT(is_tuple(token));
 	sz_token = size_object(token);
-	bp = new_message_buffer(term_size+sz_token);
-	hp = bp->mem;
-	mess = copy_struct(exit_term, term_size, &hp, &bp->off_heap);
+
+	mp = erts_alloc_message_heap(to, to_locksp,
+				     term_size+sz_token, &hp, &ohp);
+	mess = copy_struct(exit_term, term_size, &hp, ohp);
 	/* the trace token must in this case be updated by the caller */
 	seq_trace_output(token, mess, SEQ_TRACE_SEND, to->common.id, NULL);
-	temp_token = copy_struct(token, sz_token, &hp, &bp->off_heap);
-	erts_queue_message(to, to_locksp, bp, mess, temp_token);
+	temp_token = copy_struct(token, sz_token, &hp, ohp);
+	erts_queue_message(to, to_locksp, mp, mess, temp_token);
     }
 }
 
diff --git a/erts/emulator/beam/erl_process.h b/erts/emulator/beam/erl_process.h
index e7c5614b9c..884027f482 100644
--- a/erts/emulator/beam/erl_process.h
+++ b/erts/emulator/beam/erl_process.h
@@ -915,6 +915,7 @@ struct process {
     Eterm* stop;		/* Stack top */
     Eterm* heap;		/* Heap start */
     Eterm* hend;		/* Heap end */
+    Eterm* abandoned_heap;
     Uint heap_sz;		/* Size of heap in words */
     Uint min_heap_size;         /* Minimum size of heap (in words). */
     Uint min_vheap_size;        /* Minimum size of virtual heap (in words). */
@@ -1011,8 +1012,10 @@ struct process {
     Uint16 gen_gcs;		/* Number of (minor) generational GCs. */
     Uint16 max_gen_gcs;		/* Max minor gen GCs before fullsweep. */
     ErlOffHeap off_heap;	/* Off-heap data updated by copy_struct(). */
-    ErlHeapFragment* mbuf;	/* Pointer to message buffer list */
-    Uint mbuf_sz;		/* Size of all message buffers */
+    ErlHeapFragment* mbuf;	/* Pointer to heap fragment list */
+    ErlHeapFragment* live_hf_end;
+    ErtsMessage *msg_frag;	/* Pointer to message fragment list */
+    Uint mbuf_sz;		/* Total size of heap fragments and message fragments */
     ErtsPSD *psd;		/* Rarely used process specific data */
 
     Uint64 bin_vheap_sz;	/* Virtual heap block size for binaries */
@@ -1039,6 +1042,7 @@ struct process {
 #ifdef CHECK_FOR_HOLES
     Eterm* last_htop;		/* No need to scan the heap below this point. */
     ErlHeapFragment* last_mbuf;	/* No need to scan beyond this mbuf. */
+    ErlHeapFragment* heap_hfrag; /* Heap abandoned, htop now lives in this frag */
 #endif
 
 #ifdef DEBUG
@@ -1062,6 +1066,7 @@ extern const Process erts_invalid_process;
 do {						\
   (p)->last_htop = 0;				\
   (p)->last_mbuf = 0;				\
+  (p)->heap_hfrag = NULL;			\
 } while (0)
 
 # define ERTS_HOLE_CHECK(p) erts_check_for_holes((p))
@@ -1139,14 +1144,15 @@ void erts_check_for_holes(Process* p);
 #define ERTS_PSFLG_RUNNING_SYS		ERTS_PSFLG_BIT(15)
 #define ERTS_PSFLG_PROXY		ERTS_PSFLG_BIT(16)
 #define ERTS_PSFLG_DELAYED_SYS		ERTS_PSFLG_BIT(17)
+#define ERTS_PSFLG_OFF_HEAP_MSGQ	ERTS_PSFLG_BIT(18)
 #ifdef ERTS_DIRTY_SCHEDULERS
-#define ERTS_PSFLG_DIRTY_CPU_PROC	ERTS_PSFLG_BIT(18)
-#define ERTS_PSFLG_DIRTY_IO_PROC	ERTS_PSFLG_BIT(19)
-#define ERTS_PSFLG_DIRTY_CPU_PROC_IN_Q	ERTS_PSFLG_BIT(20)
-#define ERTS_PSFLG_DIRTY_IO_PROC_IN_Q	ERTS_PSFLG_BIT(21)
-#define ERTS_PSFLG_MAX  (ERTS_PSFLGS_ZERO_BIT_OFFSET + 22)
+#define ERTS_PSFLG_DIRTY_CPU_PROC	ERTS_PSFLG_BIT(19)
+#define ERTS_PSFLG_DIRTY_IO_PROC	ERTS_PSFLG_BIT(20)
+#define ERTS_PSFLG_DIRTY_CPU_PROC_IN_Q	ERTS_PSFLG_BIT(21)
+#define ERTS_PSFLG_DIRTY_IO_PROC_IN_Q	ERTS_PSFLG_BIT(22)
+#define ERTS_PSFLG_MAX  (ERTS_PSFLGS_ZERO_BIT_OFFSET + 23)
 #else
-#define ERTS_PSFLG_MAX  (ERTS_PSFLGS_ZERO_BIT_OFFSET + 18)
+#define ERTS_PSFLG_MAX  (ERTS_PSFLGS_ZERO_BIT_OFFSET + 19)
 #endif
 
 #define ERTS_PSFLGS_IN_PRQ_MASK 	(ERTS_PSFLG_IN_PRQ_MAX		\
@@ -1194,12 +1200,15 @@ void erts_check_for_holes(Process* p);
 #define SPO_USE_ARGS 2
 #define SPO_MONITOR 4
 #define SPO_SYSTEM_PROC 8
+#define SPO_OFF_HEAP_MSGQ 16
+
+extern int erts_default_spo_flags;
 
 /*
  * The following struct contains options for a process to be spawned.
  */
 typedef struct {
-    Uint flags;
+    int flags;
     int error_code;		/* Error code returned from create_process(). */
     Eterm mref;			/* Monitor ref returned (if SPO_MONITOR was given). */
 
@@ -1281,6 +1290,9 @@ extern struct erts_system_profile_flags_t erts_system_profile_flags;
 #define F_P2PNR_RESCHED      (1 <<  9) /* Process has been rescheduled via erts_pid2proc_not_running() */
 #define F_FORCE_GC           (1 << 10) /* Force gc at process in-scheduling */
 #define F_DISABLE_GC         (1 << 11) /* Disable GC */
+#define F_OFF_HEAP_MSGQ      (1 << 12) /* Off heap msg queue */
+#define F_OFF_HEAP_MSGQ_CHNG (1 << 13) /* Off heap msg queue changing */
+#define F_ABANDONED_HEAP_USE (1 << 14) /* Have usage of abandoned heap */
 
 /* process trace_flags */
 #define F_SENSITIVE          (1 << 0)
@@ -1614,6 +1626,7 @@ void erts_schedule_thr_prgr_later_cleanup_op(void (*)(void *),
 					     void *,
 					     ErtsThrPrgrLaterOp *,
 					     UWord);
+void erts_schedule_complete_off_heap_message_queue_change(Eterm pid);
 
 #if defined(ERTS_SMP) && defined(ERTS_ENABLE_LOCK_CHECK)
 int erts_dbg_check_halloc_lock(Process *p);
@@ -1741,7 +1754,7 @@ Uint erts_debug_nbalance(void);
 
 int erts_debug_wait_completed(Process *c_p, int flags);
 
-Uint erts_process_memory(Process *c_p);
+Uint erts_process_memory(Process *c_p, int incl_msg_inq);
 
 #ifdef ERTS_SMP
 #  define ERTS_GET_SCHEDULER_DATA_FROM_PROC(PROC) ((PROC)->scheduler_data)
@@ -2056,6 +2069,22 @@ ERTS_GLB_INLINE void erts_smp_xrunq_unlock(ErtsRunQueue *rq, ErtsRunQueue *xrq);
 ERTS_GLB_INLINE void erts_smp_runqs_lock(ErtsRunQueue *rq1, ErtsRunQueue *rq2);
 ERTS_GLB_INLINE void erts_smp_runqs_unlock(ErtsRunQueue *rq1, ErtsRunQueue *rq2);
 
+ERTS_GLB_INLINE ErtsMessage *erts_alloc_message_heap_state(Process *pp,
+							   erts_aint32_t *psp,
+							   ErtsProcLocks *plp,
+							   Uint sz,
+							   Eterm **hpp,
+							   ErlOffHeap **ohpp);
+ERTS_GLB_INLINE ErtsMessage *erts_alloc_message_heap(Process *pp,
+						     ErtsProcLocks *plp,
+						     Uint sz,
+						     Eterm **hpp,
+						     ErlOffHeap **ohpp);
+
+ERTS_GLB_INLINE void erts_shrink_message_heap(ErtsMessage **msgpp, Process *pp,
+					      Eterm *start_hp, Eterm *used_hp, Eterm *end_hp,
+					      Eterm *brefs, Uint brefs_size);
+
 #if ERTS_GLB_INLINE_INCL_FUNC_DEF
 
 ERTS_GLB_INLINE
@@ -2204,6 +2233,63 @@ erts_smp_runqs_unlock(ErtsRunQueue *rq1, ErtsRunQueue *rq2)
 #endif
 }
 
+ERTS_GLB_INLINE ErtsMessage *
+erts_alloc_message_heap_state(Process *pp,
+			      erts_aint32_t *psp,
+			      ErtsProcLocks *plp,
+			      Uint sz,
+			      Eterm **hpp,
+			      ErlOffHeap **ohpp)
+{
+    int on_heap;
+
+    if ((*psp) & ERTS_PSFLG_OFF_HEAP_MSGQ) {
+	ErtsMessage *mp = erts_alloc_message(sz, hpp);
+	*ohpp = sz == 0 ? NULL : &mp->hfrag.off_heap;
+	return mp;
+    }
+
+    return erts_try_alloc_message_on_heap(pp, psp, plp, sz, hpp, ohpp, &on_heap);
+}
+
+ERTS_GLB_INLINE ErtsMessage *
+erts_alloc_message_heap(Process *pp,
+			ErtsProcLocks *plp,
+			Uint sz,
+			Eterm **hpp,
+			ErlOffHeap **ohpp)
+{
+    erts_aint32_t state = erts_smp_atomic32_read_nob(&pp->state);
+    return erts_alloc_message_heap_state(pp, &state, plp, sz, hpp, ohpp);
+}
+
+ERTS_GLB_INLINE void
+erts_shrink_message_heap(ErtsMessage **msgpp, Process *pp,
+			 Eterm *start_hp, Eterm *used_hp, Eterm *end_hp,
+			 Eterm *brefs, Uint brefs_size)
+{
+    ASSERT(start_hp <= used_hp && used_hp <= end_hp);
+    if ((*msgpp)->data.attached == ERTS_MSG_COMBINED_HFRAG)
+	*msgpp = erts_shrink_message(*msgpp, used_hp - start_hp,
+				     brefs, brefs_size);
+    else if (!(*msgpp)->data.attached) {
+	ERTS_SMP_LC_ASSERT(ERTS_PROC_LOCK_MAIN
+			   & erts_proc_lc_my_proc_locks(pp));
+	HRelease(pp, end_hp, used_hp);
+    }
+    else {
+	ErlHeapFragment *hfrag = (*msgpp)->data.heap_frag;
+	if (start_hp != used_hp)
+	    hfrag = erts_resize_message_buffer(hfrag, used_hp - start_hp,
+					       brefs, brefs_size);
+	else {
+	    free_message_buffer(hfrag);
+	    hfrag = NULL;
+	}
+	(*msgpp)->data.heap_frag = hfrag;
+    }
+}
+
 #endif /* #if ERTS_GLB_INLINE_INCL_FUNC_DEF */
 
 ERTS_GLB_INLINE ErtsAtomCacheMap *erts_get_atom_cache_map(Process *c_p);
diff --git a/erts/emulator/beam/erl_process_dump.c b/erts/emulator/beam/erl_process_dump.c
index 3b8ae11e94..71396561a3 100644
--- a/erts/emulator/beam/erl_process_dump.c
+++ b/erts/emulator/beam/erl_process_dump.c
@@ -78,13 +78,14 @@ erts_deep_process_dump(int to, void *to_arg)
     dump_binaries(to, to_arg, all_binaries);
 }
 
-Uint erts_process_memory(Process *p) {
-  ErlMessage *mp;
+Uint erts_process_memory(Process *p, int incl_msg_inq) {
+  ErtsMessage *mp;
   Uint size = 0;
   struct saved_calls *scb;
   size += sizeof(Process);
 
-  ERTS_SMP_MSGQ_MV_INQ2PRIVQ(p);
+  if (incl_msg_inq)
+      ERTS_SMP_MSGQ_MV_INQ2PRIVQ(p);
 
   erts_doforall_links(ERTS_P_LINKS(p), &erts_one_link_size, &size);
   erts_doforall_monitors(ERTS_P_MONITORS(p), &erts_one_mon_size, &size);
@@ -92,7 +93,7 @@ Uint erts_process_memory(Process *p) {
   if (p->old_hend && p->old_heap)
     size += (p->old_hend - p->old_heap) * sizeof(Eterm);
 
-  size += p->msg.len * sizeof(ErlMessage);
+  size += p->msg.len * sizeof(ErtsMessage);
 
   for (mp = p->msg.first; mp; mp = mp->next)
     if (mp->data.attached)
@@ -119,7 +120,7 @@ static void
 dump_process_info(int to, void *to_arg, Process *p)
 {
     Eterm* sp;
-    ErlMessage* mp;
+    ErtsMessage* mp;
     int yreg = -1;
 
     ERTS_SMP_MSGQ_MV_INQ2PRIVQ(p);
@@ -657,6 +658,8 @@ erts_dump_extended_process_state(int to, void *to_arg, erts_aint32_t psflg) {
                 erts_print(to, to_arg, "PROXY"); break;
             case ERTS_PSFLG_DELAYED_SYS:
                 erts_print(to, to_arg, "DELAYED_SYS"); break;
+            case ERTS_PSFLG_OFF_HEAP_MSGQ:
+                erts_print(to, to_arg, "OFF_HEAP_MSGQ"); break;
 #ifdef ERTS_DIRTY_SCHEDULERS
             case ERTS_PSFLG_DIRTY_CPU_PROC:
                 erts_print(to, to_arg, "DIRTY_CPU_PROC"); break;
diff --git a/erts/emulator/beam/erl_term.c b/erts/emulator/beam/erl_term.c
index ed302fa2fa..e31d3a951d 100644
--- a/erts/emulator/beam/erl_term.c
+++ b/erts/emulator/beam/erl_term.c
@@ -28,6 +28,37 @@
 #include <stdlib.h>
 #include <stdio.h>
 
+void
+erts_set_literal_tag(Eterm *term, Eterm *hp_start, Eterm hsz)
+{
+#ifdef TAG_LITERAL_PTR
+    Eterm *hp_end, *hp;
+    
+    hp_end = hp_start + hsz;
+    hp = hp_start;
+
+    while (hp < hp_end) {
+	switch (primary_tag(*hp)) {
+	case TAG_PRIMARY_BOXED:
+	case TAG_PRIMARY_LIST:
+	    *hp |= TAG_LITERAL_PTR;
+	    break;
+	case TAG_PRIMARY_HEADER:
+	    if (header_is_thing(*hp)) {
+		hp += thing_arityval(*hp);
+	    }
+	    break;
+	default:
+	    break;
+	}
+	
+	hp++;
+    }
+    if (is_boxed(*term) || is_list(*term))
+	*term |= TAG_LITERAL_PTR;
+#endif
+}
+
 __decl_noreturn static void __noreturn
 et_abort(const char *expr, const char *file, unsigned line)
 {
diff --git a/erts/emulator/beam/erl_term.h b/erts/emulator/beam/erl_term.h
index 01ef567dcd..2b28762db5 100644
--- a/erts/emulator/beam/erl_term.h
+++ b/erts/emulator/beam/erl_term.h
@@ -21,6 +21,8 @@
 #ifndef __ERL_TERM_H
 #define __ERL_TERM_H
 
+#include "erl_mmap.h"
+
 typedef UWord Wterm;  /* Full word terms */
 
 struct erl_node_; /* Declared in erl_node_tables.h */
@@ -48,6 +50,24 @@ struct erl_node_; /* Declared in erl_node_tables.h */
 #define _ET_APPLY(F,X)	_unchecked_##F(X)
 #endif
 
+#if defined(ARCH_64)
+#  define TAG_PTR_MASK__	0x7
+#  if !defined(ERTS_HAVE_OS_PHYSICAL_MEMORY_RESERVATION)
+#    ifdef HIPE
+#      error Hipe on 64-bit needs a real mmap as it does not support the literal tag
+#    endif
+#    define TAG_LITERAL_PTR	0x4
+#  else
+#    undef TAG_LITERAL_PTR
+#  endif
+#elif defined(ARCH_32)
+#  define TAG_PTR_MASK__	0x3
+#  undef TAG_LITERAL_PTR
+#else
+#  error Not supported arch
+#endif
+
+
 #define _TAG_PRIMARY_SIZE	2
 #define _TAG_PRIMARY_MASK	0x3
 #define TAG_PRIMARY_HEADER	0x0
@@ -165,10 +185,11 @@ struct erl_node_; /* Declared in erl_node_tables.h */
 
 /* boxed object access methods */
 
-#define _is_taggable_pointer(x)	 (((Uint)(x) & 0x3) == 0)
+#define _is_taggable_pointer(x)	 (((Uint)(x) & TAG_PTR_MASK__) == 0)
+
 #define  _boxed_precond(x)       (is_boxed(x))
 
-#define _is_aligned(x)		(((Uint)(x) & 0x3) == 0)
+#define _is_aligned(x)		(((Uint)(x) & TAG_PTR_MASK__) == 0)
 #define _unchecked_make_boxed(x) ((Uint)(x) + TAG_PRIMARY_BOXED)
 _ET_DECLARE_CHECKED(Eterm,make_boxed,const Eterm*)
 #define make_boxed(x)		_ET_APPLY(make_boxed,(x))
@@ -180,7 +201,11 @@ _ET_DECLARE_CHECKED(int,is_boxed,Eterm)
 #else
 #define is_boxed(x)		(((x) & _TAG_PRIMARY_MASK) == TAG_PRIMARY_BOXED)
 #endif
+#ifdef TAG_LITERAL_PTR
+#define _unchecked_boxed_val(x) _unchecked_ptr_val(x)
+#else
 #define _unchecked_boxed_val(x) ((Eterm*) ((x) - TAG_PRIMARY_BOXED))
+#endif
 _ET_DECLARE_CHECKED(Eterm*,boxed_val,Wterm)
 #define boxed_val(x)		_ET_APPLY(boxed_val,(x))
 
@@ -198,7 +223,11 @@ _ET_DECLARE_CHECKED(int,is_not_list,Eterm)
 #define is_not_list(x)		(!is_list((x)))
 #endif
 #define _list_precond(x)        (is_list(x))
+#ifdef TAG_LITERAL_PTR
+#define _unchecked_list_val(x) _unchecked_ptr_val(x)
+#else
 #define _unchecked_list_val(x) ((Eterm*) ((x) - TAG_PRIMARY_LIST))
+#endif
 _ET_DECLARE_CHECKED(Eterm*,list_val,Wterm)
 #define list_val(x)		_ET_APPLY(list_val,(x))
 
@@ -209,13 +238,20 @@ _ET_DECLARE_CHECKED(Eterm*,list_val,Wterm)
 #define CDR(x)  ((x)[1])
 
 /* generic tagged pointer (boxed or list) access methods */
-#define _unchecked_ptr_val(x)	((Eterm*) ((x) & ~((Uint) 0x3)))
+#define _unchecked_ptr_val(x)	((Eterm*) ((x) & ~((Uint) TAG_PTR_MASK__)))
 #define ptr_val(x)		_unchecked_ptr_val((x))	/*XXX*/
 #define _unchecked_offset_ptr(x,offs)	((x)+((offs)*sizeof(Eterm)))
 #define offset_ptr(x,offs)	_unchecked_offset_ptr(x,offs)	/*XXX*/
 #define _unchecked_byte_offset_ptr(x,byte_offs)	((x)+(offs))
 #define byte_offset_ptr(x,offs) _unchecked_byte_offset_ptr(x,offs)  /*XXX*/
 
+#ifdef TAG_LITERAL_PTR
+#define _unchecked_is_not_literal_ptr(x) (!((x) & TAG_LITERAL_PTR))
+#define is_not_literal_ptr(x) _unchecked_is_not_literal_ptr((x)) /*XXX*/
+#define is_literal_ptr(x) (!is_not_literal_ptr((x))) /*XXX*/
+#endif
+
+
 /* fixnum ("small") access methods */
 #if defined(ARCH_64)
 #define SMALL_BITS	(64-4)
@@ -1114,5 +1150,7 @@ extern unsigned tag_val_def(Wterm);
 
 #define is_same(A,B) ((A)==(B))
 
+void erts_set_literal_tag(Eterm *term, Eterm *hp_start, Eterm hsz);
+
 #endif	/* __ERL_TERM_H */
 
diff --git a/erts/emulator/beam/erl_time_sup.c b/erts/emulator/beam/erl_time_sup.c
index 7327e0b48c..7ec64506e8 100644
--- a/erts/emulator/beam/erl_time_sup.c
+++ b/erts/emulator/beam/erl_time_sup.c
@@ -1919,15 +1919,16 @@ send_time_offset_changed_notifications(void *new_offsetp)
 		ErtsProcLocks rp_locks = ERTS_PROC_LOCK_LINK;
 		erts_smp_proc_lock(rp, ERTS_PROC_LOCK_LINK);
 		if (erts_lookup_monitor(ERTS_P_MONITORS(rp), ref)) {
-		    ErlHeapFragment *bp;
+		    ErtsMessage *mp;
 		    ErlOffHeap *ohp;
 		    Eterm message;
 
-		    hp = erts_alloc_message_heap(hsz, &bp, &ohp, rp, &rp_locks);
+		    mp = erts_alloc_message_heap(rp, &rp_locks,
+						 hsz, &hp, &ohp);
 		    *patch_refp = ref;
 		    ASSERT(hsz == size_object(message_template));
 		    message = copy_struct(message_template, hsz, &hp, ohp);
-		    erts_queue_message(rp, &rp_locks, bp, message, NIL);
+		    erts_queue_message(rp, &rp_locks, mp, message, NIL);
 		}
 		erts_smp_proc_unlock(rp, rp_locks);
 	    }
diff --git a/erts/emulator/beam/erl_trace.c b/erts/emulator/beam/erl_trace.c
index e9dd96efc4..d02f1f7213 100644
--- a/erts/emulator/beam/erl_trace.c
+++ b/erts/emulator/beam/erl_trace.c
@@ -114,15 +114,10 @@ void erts_init_trace(void) {
 
 static Eterm system_seq_tracer;
 
-#ifdef ERTS_SMP
 #define ERTS_ALLOC_SYSMSG_HEAP(SZ, BPP, OHPP, UNUSED) \
   (*(BPP) = new_message_buffer((SZ)), \
    *(OHPP) = &(*(BPP))->off_heap, \
    (*(BPP))->mem)
-#else
-#define ERTS_ALLOC_SYSMSG_HEAP(SZ, BPP, OHPP, RPP) \
-  erts_alloc_message_heap((SZ), (BPP), (OHPP), (RPP), 0)
-#endif
 
 #ifdef ERTS_SMP
 #define ERTS_ENQ_TRACE_MSG(FPID, TPID, MSG, BP) \
@@ -131,8 +126,12 @@ do { \
     enqueue_sys_msg_unlocked(SYS_MSG_TYPE_TRACE, (FPID), (TPID), (MSG), (BP)); \
 } while(0)
 #else
-#define ERTS_ENQ_TRACE_MSG(FPID, TPROC, MSG, BP) \
-    erts_queue_message((TPROC), NULL, (BP), (MSG), NIL)
+#define ERTS_ENQ_TRACE_MSG(FPID, TPROC, MSG, BP)		\
+    do {							\
+	ErtsMessage *mp__ = erts_alloc_message(0, NULL);		\
+	mp__->data.heap_frag = (BP);				\
+	erts_queue_message((TPROC), NULL, mp__, (MSG), NIL);	\
+    } while (0)
 #endif
 
 /*
@@ -591,11 +590,9 @@ send_to_port(Process *c_p, Eterm message,
 static void 
 profile_send(Eterm from, Eterm message) {
     Uint sz = 0;
-    ErlHeapFragment *bp = NULL;
     Uint *hp = NULL;
     Eterm msg = NIL;
     Process *profile_p = NULL;
-    ErlOffHeap *off_heap = NULL;
 
     Eterm profiler = erts_get_system_profile();
 
@@ -621,6 +618,7 @@ profile_send(Eterm from, Eterm message) {
 	}
     	
     } else {
+	ErtsMessage *mp;
 	ASSERT(is_internal_pid(profiler));
         
 	profile_p = erts_proc_lookup(profiler);
@@ -629,10 +627,13 @@ profile_send(Eterm from, Eterm message) {
 	    return;
 
 	sz = size_object(message);
-	hp = erts_alloc_message_heap(sz, &bp, &off_heap, profile_p, 0);
-	msg = copy_struct(message, sz, &hp, &bp->off_heap);
-	
-        erts_queue_message(profile_p, NULL, bp, msg, NIL);
+	mp = erts_alloc_message(sz, &hp);
+	if (sz == 0)
+	    msg = message;
+	else
+	    msg = copy_struct(message, sz, &hp, &mp->hfrag.off_heap);
+
+        erts_queue_message(profile_p, NULL, mp, msg, NIL);
     }
 }
 
@@ -1233,7 +1234,11 @@ seq_trace_output_generic(Eterm token, Eterm msg, Uint type,
 	erts_smp_mtx_unlock(&smq_mtx);
 #else
         /* trace_token must be NIL here */
-	erts_queue_message(tracer, NULL, bp, mess, NIL);
+	{
+	    ErtsMessage *mp = erts_alloc_message(0, NULL);
+	    mp->data.heap_frag = bp;
+	    erts_queue_message(tracer, NULL, mp, mess, NIL);
+	}
 #endif
     }
 }
@@ -2308,7 +2313,11 @@ monitor_long_schedule_proc(Process *p, BeamInstr *in_fp, BeamInstr *out_fp, Uint
 #ifdef ERTS_SMP
     enqueue_sys_msg(SYS_MSG_TYPE_SYSMON, p->common.id, NIL, msg, bp);
 #else
-    erts_queue_message(monitor_p, NULL, bp, msg, NIL);
+    {
+	ErtsMessage *mp = erts_alloc_message(0, NULL);
+	mp->data.heap_frag = bp;
+	erts_queue_message(monitor_p, NULL, mp, msg, NIL);
+    }
 #endif
 }
 void 
@@ -2369,7 +2378,11 @@ monitor_long_schedule_port(Port *pp, ErtsPortTaskType type, Uint time)
 #ifdef ERTS_SMP
     enqueue_sys_msg(SYS_MSG_TYPE_SYSMON, pp->common.id, NIL, msg, bp);
 #else
-    erts_queue_message(monitor_p, NULL, bp, msg, NIL);
+    {
+	ErtsMessage *mp = erts_alloc_message(0, NULL);
+	mp->data.heap_frag = bp;
+	erts_queue_message(monitor_p, NULL, mp, msg, NIL);
+    }
 #endif
 }
 
@@ -2440,7 +2453,11 @@ monitor_long_gc(Process *p, Uint time) {
 #ifdef ERTS_SMP
     enqueue_sys_msg(SYS_MSG_TYPE_SYSMON, p->common.id, NIL, msg, bp);
 #else
-    erts_queue_message(monitor_p, NULL, bp, msg, NIL);
+    {
+	ErtsMessage *mp = erts_alloc_message(0, NULL);
+	mp->data.heap_frag = bp;
+	erts_queue_message(monitor_p, NULL, mp, msg, NIL);
+    }
 #endif
 }
 
@@ -2511,7 +2528,11 @@ monitor_large_heap(Process *p) {
 #ifdef ERTS_SMP
     enqueue_sys_msg(SYS_MSG_TYPE_SYSMON, p->common.id, NIL, msg, bp);
 #else
-    erts_queue_message(monitor_p, NULL, bp, msg, NIL);
+    {
+	ErtsMessage *mp = erts_alloc_message(0, NULL);
+	mp->data.heap_frag = bp;
+	erts_queue_message(monitor_p, NULL, mp, msg, NIL);
+    }
 #endif
 }
 
@@ -2539,7 +2560,11 @@ monitor_generic(Process *p, Eterm type, Eterm spec) {
 #ifdef ERTS_SMP
     enqueue_sys_msg(SYS_MSG_TYPE_SYSMON, p->common.id, NIL, msg, bp);
 #else
-    erts_queue_message(monitor_p, NULL, bp, msg, NIL);
+    {
+	ErtsMessage *mp = erts_alloc_message(0, NULL);
+	mp->data.heap_frag = bp;
+	erts_queue_message(monitor_p, NULL, mp, msg, NIL);
+    }
 #endif
 
 }
@@ -3331,8 +3356,11 @@ sys_msg_dispatcher_func(void *unused)
 		    goto failure;
 		}
 		else {
+		    ErtsMessage *mp;
 		queue_proc_msg:
-		    erts_queue_message(proc,&proc_locks,smqp->bp,smqp->msg,NIL);
+		    mp = erts_alloc_message(0, NULL);
+		    mp->data.heap_frag = smqp->bp;
+		    erts_queue_message(proc,&proc_locks,mp,smqp->msg,NIL);
 #ifdef DEBUG_PRINTOUTS
 		    erts_fprintf(stderr, "delivered\n");
 #endif
diff --git a/erts/emulator/beam/global.h b/erts/emulator/beam/global.h
index b4d02dd1dd..594c0ccf94 100644
--- a/erts/emulator/beam/global.h
+++ b/erts/emulator/beam/global.h
@@ -961,8 +961,8 @@ Uint size_object(Eterm);
 Eterm copy_struct(Eterm, Uint, Eterm**, ErlOffHeap*);
 Eterm copy_shallow(Eterm*, Uint, Eterm**, ErlOffHeap*);
 
-void move_multi_frags(Eterm** hpp, ErlOffHeap*, ErlHeapFragment* first,
-		      Eterm* refs, unsigned nrefs);
+void erts_move_multi_frags(Eterm** hpp, ErlOffHeap*, ErlHeapFragment* first,
+			   Eterm* refs, unsigned nrefs, int literals);
 
 /* Utilities */
 extern void erts_delete_nodes_monitors(Process *, ErtsProcLocks);
@@ -1274,6 +1274,27 @@ int erts_print_system_version(int to, void *arg, Process *c_p);
 
 int erts_hibernate(Process* c_p, Eterm module, Eterm function, Eterm args, Eterm* reg);
 
+ERTS_GLB_FORCE_INLINE int erts_is_literal(Eterm tptr, Eterm *ptr);
+
+#if ERTS_GLB_INLINE_INCL_FUNC_DEF
+
+ERTS_GLB_FORCE_INLINE int erts_is_literal(Eterm tptr, Eterm *ptr)
+{
+    ASSERT(is_boxed(tptr) || is_list(tptr));
+    ASSERT(ptr == ptr_val(tptr));
+
+#if defined(ERTS_HAVE_IS_IN_LITERAL_RANGE)
+    return erts_is_in_literal_range(ptr);
+#elif defined(TAG_LITERAL_PTR)
+    return is_literal_ptr(tptr);
+#else
+#  error Not able to detect literals...
+#endif
+
+}
+
+#endif
+
 /*
 ** Call_trace uses this API for the parameter matching functions
 */
@@ -1326,124 +1347,6 @@ extern erts_driver_t fd_driver;
 
 int erts_beam_jump_table(void);
 
-/* Should maybe be placed in erl_message.h, but then we get an include mess. */
-ERTS_GLB_INLINE Eterm *
-erts_alloc_message_heap_state(Uint size,
-			      ErlHeapFragment **bpp,
-			      ErlOffHeap **ohpp,
-			      Process *receiver,
-			      ErtsProcLocks *receiver_locks,
-			      erts_aint32_t *statep);
-
-ERTS_GLB_INLINE Eterm *
-erts_alloc_message_heap(Uint size,
-			ErlHeapFragment **bpp,
-			ErlOffHeap **ohpp,
-			Process *receiver,
-			ErtsProcLocks *receiver_locks);
-
-#if ERTS_GLB_INLINE_INCL_FUNC_DEF
-
-/*
- * NOTE: erts_alloc_message_heap() releases msg q and status
- *       lock on receiver without ensuring that other locks are
- *       held. User is responsible to ensure that the receiver
- *       pointer cannot become invalid until after message has
- *       been passed. This is normal done either by increasing
- *       reference count on process (preferred) or by holding
- *       main or link lock over the whole message passing
- *       operation.
- */
-
-ERTS_GLB_INLINE Eterm *
-erts_alloc_message_heap_state(Uint size,
-			      ErlHeapFragment **bpp,
-			      ErlOffHeap **ohpp,
-			      Process *receiver,
-			      ErtsProcLocks *receiver_locks,
-			      erts_aint32_t *statep)
-{
-    Eterm *hp;
-    erts_aint32_t state;
-#ifdef ERTS_SMP
-    int locked_main = 0;
-    state = erts_smp_atomic32_read_acqb(&receiver->state);
-    if (statep)
-	*statep = state;
-    if (state & (ERTS_PSFLG_EXITING
-		 | ERTS_PSFLG_PENDING_EXIT))
-	goto allocate_in_mbuf;
-#endif
-
-    if (size > (Uint) INT_MAX)
-	erl_exit(ERTS_ABORT_EXIT, "HUGE size (%beu)\n", size);
-
-    if (
-#if defined(ERTS_SMP)
-	*receiver_locks & ERTS_PROC_LOCK_MAIN
-#else
-	1
-#endif
-	) {
-#ifdef ERTS_SMP
-    try_allocate_on_heap:
-#endif
-	state = erts_smp_atomic32_read_nob(&receiver->state);
-	if (statep)
-	    *statep = state;
-	if ((state & (ERTS_PSFLG_EXITING
-		      | ERTS_PSFLG_PENDING_EXIT))
-	    || (receiver->flags & F_DISABLE_GC)
-	    || HEAP_LIMIT(receiver) - HEAP_TOP(receiver) <= size) {
-	    /*
-	     * The heap is either potentially in an inconsistent
-	     * state, or not large enough.
-	     */
-#ifdef ERTS_SMP
-	    if (locked_main) {
-		*receiver_locks &= ~ERTS_PROC_LOCK_MAIN;
-		erts_smp_proc_unlock(receiver, ERTS_PROC_LOCK_MAIN);
-	    }
-#endif
-	    goto allocate_in_mbuf;
-	}
-	hp = HEAP_TOP(receiver);
-	HEAP_TOP(receiver) = hp + size;
-	*bpp = NULL;
-	*ohpp = &MSO(receiver);
-    }
-#ifdef ERTS_SMP
-    else if (erts_smp_proc_trylock(receiver, ERTS_PROC_LOCK_MAIN) == 0) {
-	locked_main = 1;
-	*receiver_locks |= ERTS_PROC_LOCK_MAIN;
-	goto try_allocate_on_heap;
-    }
-#endif
-    else {
-	ErlHeapFragment *bp;
-    allocate_in_mbuf:
-	bp = new_message_buffer(size);
-	hp = bp->mem;
-	*bpp = bp;
-	*ohpp = &bp->off_heap;
-    }
-
-    return hp;
-}
-
-ERTS_GLB_INLINE Eterm *
-erts_alloc_message_heap(Uint size,
-			ErlHeapFragment **bpp,
-			ErlOffHeap **ohpp,
-			Process *receiver,
-			ErtsProcLocks *receiver_locks)
-{
-    return erts_alloc_message_heap_state(size, bpp, ohpp, receiver,
-					 receiver_locks, NULL);
-}
-
-#endif /* #if ERTS_GLB_INLINE_INCL_FUNC_DEF */
-
 #define DeclareTmpHeap(VariableName,Size,Process) \
      Eterm VariableName[Size]
 #define DeclareTypedTmpHeap(Type,VariableName,Process)	\
@@ -1501,6 +1404,7 @@ dtrace_fun_decode(Process *process,
     erts_snprintf(mfa_buf, DTRACE_TERM_BUF_SIZE, "%T:%T/%d",
                   module, function, arity);
 }
+
 #endif /* #if ERTS_GLB_INLINE_INCL_FUNC_DEF */
 
 #endif /* !__GLOBAL_H__ */
diff --git a/erts/emulator/beam/io.c b/erts/emulator/beam/io.c
index fdd26fcc4b..1b0c617632 100644
--- a/erts/emulator/beam/io.c
+++ b/erts/emulator/beam/io.c
@@ -1410,7 +1410,7 @@ queue_port_sched_op_reply(Process *rp,
 
     erts_factory_trim_and_close(factory, &msg, 1);
 
-    erts_queue_message(rp, rp_locksp, factory->heap_frags, msg, NIL);
+    erts_queue_message(rp, rp_locksp, factory->message, msg, NIL);
 }
 
 static void
@@ -1418,12 +1418,9 @@ port_sched_op_reply(Eterm to, Uint32 *ref_num, Eterm msg)
 {
     Process *rp = erts_proc_lookup_raw(to);
     if (rp) {
-	ErlOffHeap *ohp;
-	ErlHeapFragment* bp;
         ErtsHeapFactory factory;
 	Eterm msg_copy;
 	Uint hsz, msg_sz;
-	Eterm *hp;
 	ErtsProcLocks rp_locks = 0;
 
 	hsz = ERTS_QUEUE_PORT_SCHED_OP_REPLY_SIZE;
@@ -1434,18 +1431,13 @@ port_sched_op_reply(Eterm to, Uint32 *ref_num, Eterm msg)
 	    hsz += msg_sz;
 	}
 
-	hp = erts_alloc_message_heap(hsz,
-						&bp,
-						&ohp,
-						rp,
-						&rp_locks);
-        erts_factory_message_init(&factory, rp, hp, bp);
-	if (is_immed(msg))
-	    msg_copy = msg;
-	else {
-	    msg_copy = copy_struct(msg, msg_sz, &hp, ohp);
-            factory.hp = hp;
-        }
+	(void) erts_factory_message_create(&factory, rp,
+					   &rp_locks, hsz);
+	msg_copy = (is_immed(msg)
+		    ? msg
+		    : copy_struct(msg, msg_sz,
+				  &factory.hp,
+				  factory.off_heap));
 
 	queue_port_sched_op_reply(rp,
 				  &rp_locks,
@@ -3050,16 +3042,17 @@ deliver_result(Eterm sender, Eterm pid, Eterm res)
 
     if (rp) {
 	Eterm tuple;
-	ErlHeapFragment *bp;
+	ErtsMessage *mp;
 	ErlOffHeap *ohp;
 	Eterm* hp;
 	Uint sz_res;
 
 	sz_res = size_object(res);
-	hp = erts_alloc_message_heap(sz_res + 3, &bp, &ohp, rp, &rp_locks);
+	mp = erts_alloc_message_heap(rp, &rp_locks,
+				     sz_res + 3, &hp, &ohp);
 	res = copy_struct(res, sz_res, &hp, ohp);
 	tuple = TUPLE2(hp, sender, res);
-	erts_queue_message(rp, &rp_locks, bp, tuple, NIL);
+	erts_queue_message(rp, &rp_locks, mp, tuple, NIL);
 
 	if (rp_locks)
 	    erts_smp_proc_unlock(rp, rp_locks);
@@ -3087,7 +3080,7 @@ static void deliver_read_message(Port* prt, erts_aint32_t state, Eterm to,
     Eterm tuple;
     Process* rp;
     Eterm* hp;
-    ErlHeapFragment *bp;
+    ErtsMessage *mp;
     ErlOffHeap *ohp;
     ErtsProcLocks rp_locks = 0;
     int scheduler = erts_get_scheduler_id() != 0;
@@ -3113,7 +3106,7 @@ static void deliver_read_message(Port* prt, erts_aint32_t state, Eterm to,
     if (!rp)
 	return;
 
-    hp = erts_alloc_message_heap(need, &bp, &ohp, rp, &rp_locks);
+    mp = erts_alloc_message_heap(rp, &rp_locks, need, &hp, &ohp);
 
     listp = NIL;
     if ((state & ERTS_PORT_SFLG_BINARY_IO) == 0) {
@@ -3155,7 +3148,7 @@ static void deliver_read_message(Port* prt, erts_aint32_t state, Eterm to,
     tuple = TUPLE2(hp, prt->common.id, tuple);
     hp += 3;
 
-    erts_queue_message(rp, &rp_locks, bp, tuple, am_undefined);
+    erts_queue_message(rp, &rp_locks, mp, tuple, am_undefined);
     if (rp_locks)
 	erts_smp_proc_unlock(rp, rp_locks);
     if (!scheduler)
@@ -3229,7 +3222,7 @@ deliver_vec_message(Port* prt,			/* Port */
     Eterm tuple;
     Process* rp;
     Eterm* hp;
-    ErlHeapFragment *bp;
+    ErtsMessage *mp;
     ErlOffHeap *ohp;
     ErtsProcLocks rp_locks = 0;
     int scheduler = erts_get_scheduler_id() != 0;
@@ -3261,7 +3254,7 @@ deliver_vec_message(Port* prt,			/* Port */
 	need += (hlen+csize)*2;
     }
 
-    hp = erts_alloc_message_heap(need, &bp, &ohp, rp, &rp_locks);
+    mp = erts_alloc_message_heap(rp, &rp_locks, need, &hp, &ohp);
 
     listp = NIL;
     iov += vsize;
@@ -3322,7 +3315,7 @@ deliver_vec_message(Port* prt,			/* Port */
     tuple = TUPLE2(hp, prt->common.id, tuple);
     hp += 3;
 
-    erts_queue_message(rp, &rp_locks, bp, tuple, am_undefined);
+    erts_queue_message(rp, &rp_locks, mp, tuple, am_undefined);
     erts_smp_proc_unlock(rp, rp_locks);
     if (!scheduler)
 	erts_proc_dec_refc(rp);
@@ -3813,7 +3806,6 @@ write_port_control_result(int control_flags,
 			  ErlDrvSizeT resp_size,
 			  char *pre_alloc_buf,
 			  Eterm **hpp,
-			  ErlHeapFragment *bp,
 			  ErlOffHeap *ohp)
 {
     Eterm res;
@@ -3887,9 +3879,6 @@ port_sig_control(Port *prt,
 
 	if (res == ERTS_PORT_OP_DONE) {
 	    Eterm msg;
-	    Eterm *hp;
-	    ErlHeapFragment *bp;
-	    ErlOffHeap *ohp;
             ErtsHeapFactory factory;
 	    Process *rp;
 	    ErtsProcLocks rp_locks = 0;
@@ -3909,22 +3898,15 @@ port_sig_control(Port *prt,
 	    hsz = rsz + ERTS_QUEUE_PORT_SCHED_OP_REPLY_SIZE;
 
 
-	    hp = erts_alloc_message_heap(hsz,
-						    &bp,
-						    &ohp,
-						    rp,
-						    &rp_locks);
-            erts_factory_message_init(&factory, rp, hp, bp);
+	    (void) erts_factory_message_create(&factory, rp,
+					       &rp_locks, hsz);
 
 	    msg = write_port_control_result(control_flags,
 					    resp_bufp,
 					    resp_size,
 					    &resp_buf[0],
-					    &hp,
-					    bp,
-					    ohp);
-            factory.hp = hp;
-
+					    &factory.hp,
+					    factory.off_heap);
 	    queue_port_sched_op_reply(rp,
 				      &rp_locks,
                                       &factory,
@@ -4065,7 +4047,6 @@ erts_port_control(Process* c_p,
 						 resp_size,
 						 &resp_buf[0],
 						 &hp,
-						 NULL,
 						 &c_p->off_heap);
 	    BUMP_REDS(c_p, ERTS_PORT_REDS_CONTROL);
 	    return ERTS_PORT_OP_DONE;
@@ -4224,21 +4205,14 @@ port_sig_call(Port *prt,
 
 	    hsz = erts_decode_ext_size((byte *) resp_bufp, resp_size);
 	    if (hsz >= 0) {
-                ErlHeapFragment* bp;
-                ErlOffHeap* ohp;
                 ErtsHeapFactory factory;
 		byte *endp;
 
 		hsz += 3; /* ok tuple */
 		hsz += ERTS_QUEUE_PORT_SCHED_OP_REPLY_SIZE;
 
-                hp = erts_alloc_message_heap(hsz,
-                                             &bp,
-                                             &ohp,
-                                             rp,
-                                             &rp_locks);
+                (void) erts_factory_message_create(&factory, rp, &rp_locks, hsz);
 		endp = (byte *) resp_bufp;
-                erts_factory_message_init(&factory, rp, hp, bp);
 		msg = erts_decode_ext(&factory, &endp);
 		if (is_value(msg)) {
                     hp = erts_produce_heap(&factory,
@@ -4499,7 +4473,9 @@ port_sig_info(Port *prt,
 				    sigdp->u.info.item);
 	if (is_value(value)) {
             ErtsHeapFactory factory;
-            erts_factory_message_init(&factory, NULL, hp, bp);
+	    ErtsMessage *mp = erts_alloc_message(0, NULL);
+	    mp->data.heap_frag = bp;
+            erts_factory_selfcontained_message_init(&factory, mp, hp);
 	    queue_port_sched_op_reply(rp,
 				      &rp_locks,
                                       &factory,
@@ -4587,8 +4563,8 @@ reply_io_bytes(void *vreq)
 
     rp = erts_proc_lookup(req->pid);
     if (rp) {
-	ErlOffHeap *ohp = NULL;
-	ErlHeapFragment *bp = NULL;
+	ErlOffHeap *ohp;
+	ErtsMessage *mp;
 	ErtsProcLocks rp_locks;
 	Eterm ref, msg, ein, eout, *hp;
 	Uint64 in, out;
@@ -4610,7 +4586,7 @@ reply_io_bytes(void *vreq)
 	erts_bld_uint64(NULL, &hsz, in);
 	erts_bld_uint64(NULL, &hsz, out);
 
-	hp = erts_alloc_message_heap(hsz, &bp, &ohp, rp, &rp_locks);
+	mp = erts_alloc_message_heap(rp, &rp_locks, hsz, &hp, &ohp);
 
 	ref = make_internal_ref(hp);
 	write_ref_thing(hp, req->refn[0], req->refn[1], req->refn[2]);
@@ -4620,7 +4596,7 @@ reply_io_bytes(void *vreq)
 	eout = erts_bld_uint64(&hp, NULL, out);
 
 	msg = TUPLE4(hp, ref, make_small(sched_id), ein, eout);
-	erts_queue_message(rp, &rp_locks, bp, msg, NIL);
+	erts_queue_message(rp, &rp_locks, mp, msg, NIL);
 
 	if (req->sched_id == sched_id)
 	    rp_locks &= ~ERTS_PROC_LOCK_MAIN;
@@ -5065,11 +5041,11 @@ ErlDrvTermData driver_mk_term_nil(void)
 void driver_report_exit(ErlDrvPort ix, int status)
 {
    Eterm* hp;
+   ErlOffHeap *ohp;
    Eterm tuple;
    Process *rp;
    Eterm pid;
-   ErlHeapFragment *bp = NULL;
-   ErlOffHeap *ohp;
+   ErtsMessage *mp;
    ErtsProcLocks rp_locks = 0;
    int scheduler = erts_get_scheduler_id() != 0;
    Port* prt = erts_drvport2port(ix);
@@ -5089,13 +5065,13 @@ void driver_report_exit(ErlDrvPort ix, int status)
    if (!rp)
        return;
 
-   hp = erts_alloc_message_heap(3+3, &bp, &ohp, rp, &rp_locks);
+   mp = erts_alloc_message_heap(rp, &rp_locks, 3+3, &hp, &ohp);
 
    tuple = TUPLE2(hp, am_exit_status, make_small(status));
    hp += 3;
    tuple = TUPLE2(hp, prt->common.id, tuple);
 
-   erts_queue_message(rp, &rp_locks, bp, tuple, am_undefined);
+   erts_queue_message(rp, &rp_locks, mp, tuple, am_undefined);
 
    erts_smp_proc_unlock(rp, rp_locks);
    if (!scheduler)
@@ -5205,7 +5181,6 @@ driver_deliver_term(Eterm to, ErlDrvTermData* data, int len)
     ErtsProcLocks rp_locks = 0;
     struct b2t_states__ b2t;
     int scheduler;
-    int is_heap_need_limited = 1;
     ErtsSchedulerData *esdp = erts_get_scheduler_data();
 
     ERTS_UNDEF(mess,NIL);
@@ -5374,9 +5349,6 @@ driver_deliver_term(Eterm to, ErlDrvTermData* data, int len)
 	    need += hsz;
 	    ptr += 2;
 	    depth++;
-            if (size > MAP_SMALL_MAP_LIMIT*3) { /* may contain big map */
-                is_heap_need_limited = 0;
-            }
 	    break;
 	}
 	case ERL_DRV_MAP: { /* int */
@@ -5384,7 +5356,6 @@ driver_deliver_term(Eterm to, ErlDrvTermData* data, int len)
 	    if ((int) ptr[0] < 0) ERTS_DDT_FAIL;
             if (ptr[0] > MAP_SMALL_MAP_LIMIT) {
                 need += HASHMAP_ESTIMATED_HEAP_SIZE(ptr[0]);
-                is_heap_need_limited = 0;
             } else {
                 need += MAP_HEADER_FLATMAP_SZ + 1 + 2*ptr[0];
             }
@@ -5423,17 +5394,7 @@ driver_deliver_term(Eterm to, ErlDrvTermData* data, int len)
 	goto done;
     }
 
-    /* Try copy directly to destination heap if we know there are no big maps */
-    if (is_heap_need_limited) {
-        ErlOffHeap *ohp;
-        ErlHeapFragment* bp;
-        Eterm* hp = erts_alloc_message_heap(need, &bp, &ohp, rp, &rp_locks);
-        erts_factory_message_init(&factory, rp, hp, bp);
-    }
-    else {
-        erts_factory_message_init(&factory, NULL, NULL,
-                                  new_message_buffer(need));
-    }
+    (void) erts_factory_message_create(&factory, rp, &rp_locks, need);
 
     /*
      * Interpret the instructions and build the term.
@@ -5702,9 +5663,9 @@ driver_deliver_term(Eterm to, ErlDrvTermData* data, int len)
 
     if (res > 0) {
 	mess = ESTACK_POP(stack);  /* get resulting value */
-	erts_factory_close(&factory);
+	erts_factory_trim_and_close(&factory, &mess, 1);
 	/* send message */
-	erts_queue_message(rp, &rp_locks, factory.heap_frags, mess, am_undefined);
+	erts_queue_message(rp, &rp_locks, factory.message, mess, am_undefined);
     }
     else {
 	if (b2t.ix > b2t.used)
diff --git a/erts/emulator/beam/sys.h b/erts/emulator/beam/sys.h
index 46577bd07f..90e16ca14f 100644
--- a/erts/emulator/beam/sys.h
+++ b/erts/emulator/beam/sys.h
@@ -21,6 +21,19 @@
 #ifndef __SYS_H__
 #define __SYS_H__
 
+#if !defined(__GNUC__)
+#  define ERTS_AT_LEAST_GCC_VSN__(MAJ, MIN, PL) 0
+#elif !defined(__GNUC_MINOR__)
+#  define ERTS_AT_LEAST_GCC_VSN__(MAJ, MIN, PL) \
+  ((__GNUC__ << 24) >= (((MAJ) << 24) | ((MIN) << 12) | (PL)))
+#elif !defined(__GNUC_PATCHLEVEL__)
+#  define ERTS_AT_LEAST_GCC_VSN__(MAJ, MIN, PL) \
+  (((__GNUC__ << 24) | (__GNUC_MINOR__ << 12)) >= (((MAJ) << 24) | ((MIN) << 12) | (PL)))
+#else
+#  define ERTS_AT_LEAST_GCC_VSN__(MAJ, MIN, PL) \
+  (((__GNUC__ << 24) | (__GNUC_MINOR__ << 12) | __GNUC_PATCHLEVEL__) >= (((MAJ) << 24) | ((MIN) << 12) | (PL)))
+#endif
+
 #ifdef ERTS_INLINE
 #  ifndef ERTS_CAN_INLINE
 #    define ERTS_CAN_INLINE 1
@@ -38,6 +51,17 @@
 #  endif
 #endif
 
+#ifndef ERTS_FORCE_INLINE
+#  if ERTS_AT_LEAST_GCC_VSN__(3,1,1)
+#    define ERTS_FORCE_INLINE __inline__ __attribute__((__always_inline__))
+#  elif defined(__WIN32__)
+#    define ERTS_FORCE_INLINE __forceinline
+#  endif
+#  ifndef ERTS_FORCE_INLINE
+#    define ERTS_FORCE_INLINE ERTS_INLINE
+#  endif
+#endif
+
 #if defined(DEBUG) || defined(ERTS_ENABLE_LOCK_CHECK)
 #  undef ERTS_CAN_INLINE
 #  define ERTS_CAN_INLINE 0
@@ -46,8 +70,10 @@
 #endif
 
 #if ERTS_CAN_INLINE
+#define ERTS_GLB_FORCE_INLINE static ERTS_FORCE_INLINE
 #define ERTS_GLB_INLINE static ERTS_INLINE
 #else
+#define ERTS_GLB_FORCE_INLINE
 #define ERTS_GLB_INLINE
 #endif
 
@@ -72,6 +98,9 @@
 
 #define ERTS_I64_LITERAL(X) X##LL
 
+#define ErtsInArea(ptr,start,nbytes) \
+    ((UWord)((char*)(ptr) - (char*)(start)) < (nbytes))
+
 #if defined (__WIN32__)
 #  include "erl_win_sys.h"
 #else
@@ -109,19 +138,6 @@ typedef int ErtsSysFdType;
 typedef ERTS_SYS_FD_TYPE ErtsSysFdType;
 #endif
 
-#if !defined(__GNUC__)
-#  define ERTS_AT_LEAST_GCC_VSN__(MAJ, MIN, PL) 0
-#elif !defined(__GNUC_MINOR__)
-#  define ERTS_AT_LEAST_GCC_VSN__(MAJ, MIN, PL) \
-  ((__GNUC__ << 24) >= (((MAJ) << 24) | ((MIN) << 12) | (PL)))
-#elif !defined(__GNUC_PATCHLEVEL__)
-#  define ERTS_AT_LEAST_GCC_VSN__(MAJ, MIN, PL) \
-  (((__GNUC__ << 24) | (__GNUC_MINOR__ << 12)) >= (((MAJ) << 24) | ((MIN) << 12) | (PL)))
-#else
-#  define ERTS_AT_LEAST_GCC_VSN__(MAJ, MIN, PL) \
-  (((__GNUC__ << 24) | (__GNUC_MINOR__ << 12) | __GNUC_PATCHLEVEL__) >= (((MAJ) << 24) | ((MIN) << 12) | (PL)))
-#endif
-
 #if ERTS_AT_LEAST_GCC_VSN__(2, 96, 0)
 #  define ERTS_LIKELY(BOOL)   __builtin_expect((BOOL), !0)
 #  define ERTS_UNLIKELY(BOOL) __builtin_expect((BOOL), 0)
@@ -1044,10 +1060,6 @@ extern int erts_use_kernel_poll;
 
 #define put_int8(i, s) do {((unsigned char*)(s))[0] = (i) & 0xff;} while (0)
 
-
-#define ErtsInArea(PTR,START,NBYTES) \
-    ((UWord)((char*)(PTR) - (char*)(START)) < (NBYTES))
-
 /*
  * Use DEBUGF as you would use printf, but use double parentheses:
  *
diff --git a/erts/emulator/beam/utils.c b/erts/emulator/beam/utils.c
index 5fe4091adc..c3735683bb 100644
--- a/erts/emulator/beam/utils.c
+++ b/erts/emulator/beam/utils.c
@@ -110,7 +110,6 @@ Eterm*
 erts_heap_alloc(Process* p, Uint need, Uint xtra)
 {
     ErlHeapFragment* bp;
-    Eterm* htop;
     Uint n;
 #if defined(DEBUG) || defined(CHECK_FOR_HOLES)
     Uint i;
@@ -156,16 +155,6 @@ erts_heap_alloc(Process* p, Uint need, Uint xtra)
     n--;
 #endif
 
-    /*
-     * When we have created a heap fragment, we are no longer allowed
-     * to store anything more on the heap. 
-     */
-    htop = HEAP_TOP(p);
-    if (htop < HEAP_LIMIT(p)) {
-	*htop = make_pos_bignum_header(HEAP_LIMIT(p)-htop-1);
-	HEAP_TOP(p) = HEAP_LIMIT(p);
-    }
-
     bp->next = MBUF(p);
     MBUF(p) = bp;
     bp->alloc_size = n;
@@ -2284,7 +2273,11 @@ static void do_send_logger_message(Eterm *hp, ErlOffHeap *ohp, ErlHeapFragment *
 	erts_queue_error_logger_message(from, message, bp);
     }
 #else
-    erts_queue_message(p, NULL /* only used for smp build */, bp, message, NIL);
+    {
+	ErtsMessage *mp = erts_alloc_message(0, NULL);
+	mp->data.heap_frag = bp;
+	erts_queue_message(p, NULL /* only used for smp build */, mp, message, NIL);
+    }
 #endif
 }
 
diff --git a/erts/emulator/hipe/hipe_bif0.c b/erts/emulator/hipe/hipe_bif0.c
index c6ea8a5132..00936b6b8a 100644
--- a/erts/emulator/hipe/hipe_bif0.c
+++ b/erts/emulator/hipe/hipe_bif0.c
@@ -497,6 +497,8 @@ static void *const_term_alloc(void *tmpl)
     hp = &p->mem[0];
     p->val = copy_struct(obj, size, &hp, &const_term_table_off_heap);
 
+    erts_set_literal_tag(&p->val, &p->mem[0], size);
+
     return &p->bucket;
 }
 
diff --git a/erts/emulator/hipe/hipe_gc.c b/erts/emulator/hipe/hipe_gc.c
index 2c747771ac..2e19bf88bf 100644
--- a/erts/emulator/hipe/hipe_gc.c
+++ b/erts/emulator/hipe/hipe_gc.c
@@ -46,10 +46,6 @@ Eterm *fullsweep_nstack(Process *p, Eterm *n_htop)
     /* arch-specific nstack walk state */
     struct nstack_walk_state walk_state;
 
-    /* fullsweep-specific state */
-    char *src, *oh;
-    Uint src_size, oh_size;
-
     if (!p->hipe.nstack) {
 	ASSERT(!p->hipe.nsp && !p->hipe.nstend);
 	return n_htop;
@@ -66,11 +62,6 @@ Eterm *fullsweep_nstack(Process *p, Eterm *n_htop)
 
     sdesc = nstack_walk_init_sdesc(p, &walk_state);
 
-    src = (char*)HEAP_START(p);
-    src_size = (char*)HEAP_TOP(p) - src;
-    oh = (char*)OLD_HEAP(p);
-    oh_size = (char*)OLD_HTOP(p) - oh;
-
     for (;;) {
 	if (nstack_walk_nsp_reached_end(nsp, nsp_end)) {
 	    if (nsp == nsp_end) {
@@ -97,8 +88,7 @@ Eterm *fullsweep_nstack(Process *p, Eterm *n_htop)
 		    if (IS_MOVED_BOXED(val)) {
 			ASSERT(is_boxed(val));
 			*nsp_i = val;
-		    } else if (in_area(ptr, src, src_size) ||
-			       in_area(ptr, oh, oh_size)) {
+		    } else if (!erts_is_literal(gval, ptr)) {
 			MOVE_BOXED(ptr, val, n_htop, nsp_i);
 		    }
 		} else if (is_list(gval)) {
@@ -106,8 +96,7 @@ Eterm *fullsweep_nstack(Process *p, Eterm *n_htop)
 		    Eterm val = *ptr;
 		    if (IS_MOVED_CONS(val)) {
 			*nsp_i = ptr[1];
-		    } else if (in_area(ptr, src, src_size) ||
-			       in_area(ptr, oh, oh_size)) {
+		    } else if (!erts_is_literal(gval, ptr)) {
 			ASSERT(within(ptr, p));
 			MOVE_CONS(ptr, val, n_htop, nsp_i);
 		    }
@@ -139,11 +128,13 @@ void gensweep_nstack(Process *p, Eterm **ptr_old_htop, Eterm **ptr_n_htop)
     unsigned int mask;
     /* arch-specific nstack walk state */
     struct nstack_walk_state walk_state;
+    char *oh;
+    Uint oh_size;
 
     /* gensweep-specific state */
     Eterm *old_htop, *n_htop;
-    char *heap;
-    Uint heap_size, mature_size;
+    char *mature;
+    Uint mature_size;
 
     if (!p->hipe.nstack) {
 	ASSERT(!p->hipe.nsp && !p->hipe.nstend);
@@ -168,9 +159,10 @@ void gensweep_nstack(Process *p, Eterm **ptr_old_htop, Eterm **ptr_n_htop)
 
     old_htop = *ptr_old_htop;
     n_htop = *ptr_n_htop;
-    heap = (char*)HEAP_START(p);
-    heap_size = (char*)HEAP_TOP(p) - heap;
-    mature_size = (char*)HIGH_WATER(p) - heap;
+    mature = (char *) (p->abandoned_heap ? p->abandoned_heap : p->heap);
+    mature_size = (char*)HIGH_WATER(p) - mature;
+    oh = (char*)OLD_HEAP(p);
+    oh_size = (char*)OLD_HTOP(p) - oh;
 
     for (;;) {
 	if (nstack_walk_nsp_reached_end(nsp, nsp_end)) {
@@ -209,9 +201,9 @@ void gensweep_nstack(Process *p, Eterm **ptr_old_htop, Eterm **ptr_n_htop)
 		    if (IS_MOVED_BOXED(val)) {
 			ASSERT(is_boxed(val));
 			*nsp_i = val;
-		    } else if (in_area(ptr, heap, mature_size)) {
+		    } else if (ErtsInArea(ptr, mature, mature_size)) {
 			MOVE_BOXED(ptr, val, old_htop, nsp_i);
-		    } else if (in_area(ptr, heap, heap_size)) {
+		    } else if (ErtsInYoungGen(gval, ptr, oh, oh_size)) {
 			ASSERT(within(ptr, p));
 			MOVE_BOXED(ptr, val, n_htop, nsp_i);
 		    }
@@ -220,9 +212,9 @@ void gensweep_nstack(Process *p, Eterm **ptr_old_htop, Eterm **ptr_n_htop)
 		    Eterm val = *ptr;
 		    if (IS_MOVED_CONS(val)) {
 			*nsp_i = ptr[1];
-		    } else if (in_area(ptr, heap, mature_size)) {
+		    } else if (ErtsInArea(ptr, mature, mature_size)) {
 			MOVE_CONS(ptr, val, old_htop, nsp_i);
-		    } else if (in_area(ptr, heap, heap_size)) {
+		    } else if (ErtsInYoungGen(gval, ptr, oh, oh_size)) {
 			ASSERT(within(ptr, p));
 			MOVE_CONS(ptr, val, n_htop, nsp_i);
 		    }
diff --git a/erts/emulator/hipe/hipe_native_bif.c b/erts/emulator/hipe/hipe_native_bif.c
index 688378b2fe..089c0cc662 100644
--- a/erts/emulator/hipe/hipe_native_bif.c
+++ b/erts/emulator/hipe/hipe_native_bif.c
@@ -157,13 +157,22 @@ BIF_RETTYPE hipe_set_timeout(BIF_ALIST_1)
  */
 void hipe_select_msg(Process *p)
 {
-    ErlMessage *msgp;
+    ErtsMessage *msgp;
 
     msgp = PEEK_MESSAGE(p);
     UNLINK_MESSAGE(p, msgp);	/* decrements global 'erts_proc_tot_mem' variable */
     JOIN_MESSAGE(p);
     CANCEL_TIMER(p);		/* calls erts_cancel_proc_timer() */
-    free_message(msgp);
+    erts_save_message_in_proc(p, msgp);
+    p->flags &= ~F_DISABLE_GC;
+    if (ERTS_IS_GC_DESIRED(p)) {
+	/*
+	 * We want to GC soon but we leave a few
+	 * reductions giving the message some time
+	 * to turn into garbage.
+	 */
+	ERTS_VBUMP_LEAVE_REDS(p, 5);
+    }
 }
 
 void hipe_fclearerror_error(Process *p)
@@ -508,8 +517,9 @@ int hipe_bs_validate_unicode_retract(ErlBinMatchBuffer* mb, Eterm arg)
  */
 Eterm hipe_check_get_msg(Process *c_p)
 {
-    Eterm ret;
-    ErlMessage *msgp;
+    ErtsMessage *msgp;
+
+    c_p->flags |= F_DISABLE_GC;
 
  next_message:
 
@@ -531,25 +541,29 @@ Eterm hipe_check_get_msg(Process *c_p)
 	    /* XXX: BEAM doesn't need this */
 	    c_p->hipe_smp.have_receive_locks = 1;
 #endif
+	    c_p->flags &= ~F_DISABLE_GC;
 	    return THE_NON_VALUE;
 #ifdef ERTS_SMP
 	}
 #endif
     }
-    ErtsMoveMsgAttachmentIntoProc(msgp, c_p, c_p->stop, HEAP_TOP(c_p),
-				  c_p->fcalls, (void) 0, (void) 0);
-    ret = ERL_MESSAGE_TERM(msgp);
-    if (is_non_value(ret)) {
+
+    if (is_non_value(ERL_MESSAGE_TERM(msgp))
+	&& !erts_decode_dist_message(c_p, ERTS_PROC_LOCK_MAIN, msgp, 0)) {
 	/*
 	 * A corrupt distribution message that we weren't able to decode;
 	 * remove it...
 	 */
 	ASSERT(!msgp->data.attached);
 	UNLINK_MESSAGE(c_p, msgp);
-	free_message(msgp);
+	msgp->next = NULL;
+	erts_cleanup_messages(msgp);
 	goto next_message;
     }
-    return ret;
+
+    ASSERT(is_value(ERL_MESSAGE_TERM(msgp)));
+
+    return ERL_MESSAGE_TERM(msgp);
 }
 
 /*
diff --git a/erts/etc/common/erlexec.c b/erts/etc/common/erlexec.c
index cde0b25a2a..461957be10 100644
--- a/erts/etc/common/erlexec.c
+++ b/erts/etc/common/erlexec.c
@@ -155,6 +155,12 @@ static char *plusr_val_switches[] = {
     NULL
 };
 
+/* +x arguments with values */
+static char *plusx_val_switches[] = {
+    "ohmq",
+    NULL
+};
+
 /* +z arguments with values */
 static char *plusz_val_switches[] = {
     "dbbl",
@@ -975,6 +981,20 @@ int main(int argc, char **argv)
 		      add_Eargs(argv[i+1]);
 		      i++;
 		      break;
+		  case 'x':
+		      if (!is_one_of_strings(&argv[i][2], plusx_val_switches)) {
+			  goto the_default;
+		      } else {
+			  if (i+1 >= argc
+			      || argv[i+1][0] == '-'
+			      || argv[i+1][0] == '+')
+			      usage(argv[i]);
+			  argv[i][0] = '-';
+			  add_Eargs(argv[i]);
+			  add_Eargs(argv[i+1]);
+			  i++;
+		      }
+		      break;
 		  case 'z':
 		      if (!is_one_of_strings(&argv[i][2], plusz_val_switches)) {
 			  goto the_default;
@@ -1175,7 +1195,7 @@ usage_aux(void)
 	  "[+S NO_SCHEDULERS:NO_SCHEDULERS_ONLINE] "
 	  "[+SP PERCENTAGE_SCHEDULERS:PERCENTAGE_SCHEDULERS_ONLINE] "
 	  "[+T LEVEL] [+V] [+v] "
-	  "[+W<i|w|e>] [+z MISC_OPTION] [args ...]\n");
+	  "[+W<i|w|e>]  [+x DEFAULT_PROC_FLAGS] [+z MISC_OPTION] [args ...]\n");
   exit(1);
 }
 
diff --git a/erts/preloaded/ebin/erlang.beam b/erts/preloaded/ebin/erlang.beam
index 863a5e61ef..641fac2d26 100644
--- a/erts/preloaded/ebin/erlang.beam
+++ b/erts/preloaded/ebin/erlang.beam
diff --git a/erts/preloaded/src/erlang.erl b/erts/preloaded/src/erlang.erl
index 7280b43502..6a9ec9c915 100644
--- a/erts/preloaded/src/erlang.erl
+++ b/erts/preloaded/src/erlang.erl
@@ -2045,6 +2045,9 @@ open_port(_PortName,_PortSettings) ->
                   (min_bin_vheap_size, MinBinVHeapSize) -> OldMinBinVHeapSize when
       MinBinVHeapSize :: non_neg_integer(),
       OldMinBinVHeapSize :: non_neg_integer();
+                  (off_heap_message_queue, OHMQ) -> OldOHMQ when
+      OHMQ :: boolean(),
+      OldOHMQ :: boolean();
                   (priority, Level) -> OldLevel when
       Level :: priority_level(),
       OldLevel :: priority_level();
@@ -2083,6 +2086,7 @@ process_flag(_Flag, _Value) ->
       min_bin_vheap_size |
       monitored_by |
       monitors |
+      off_heap_message_queue |
       priority |
       reductions |
       registered_name |
@@ -2124,6 +2128,7 @@ process_flag(_Flag, _Value) ->
       {monitors,
        Monitors :: [{process, Pid :: pid() |
                                      {RegName :: atom(), Node :: node()}}]} |
+      {off_heap_message_queue, OHMQ :: boolean()} |
       {priority, Level :: priority_level()} |
       {reductions, Number :: non_neg_integer()} |
       {registered_name, Atom :: atom()} |
@@ -2426,6 +2431,7 @@ tuple_to_list(_Tuple) ->
          (multi_scheduling) -> disabled | blocked | enabled;
          (multi_scheduling_blockers) -> [Pid :: pid()];
          (nif_version) -> string();
+         (off_heap_message_queue) -> boolean();
          (otp_release) -> string();
          (os_monotonic_time_source) -> [{atom(),term()}];
          (os_system_time_source) -> [{atom(),term()}];
@@ -2553,14 +2559,19 @@ spawn_monitor(M, F, A) when erlang:is_atom(M),
 spawn_monitor(M, F, A) ->
     erlang:error(badarg, [M,F,A]).
 
+
+-type spawn_opt_option() ::
+	link
+      | monitor
+      | {priority, Level :: priority_level()}
+      | {fullsweep_after, Number :: non_neg_integer()}
+      | {min_heap_size, Size :: non_neg_integer()}
+      | {min_bin_vheap_size, VSize :: non_neg_integer()}
+      | {off_heap_message_queue, OHMQ :: boolean()}.
+
 -spec spawn_opt(Fun, Options) -> pid() | {pid(), reference()} when
       Fun :: function(),
-      Options :: [Option],
-      Option :: link | monitor
-              | {priority, Level :: priority_level()}
-              | {fullsweep_after, Number :: non_neg_integer()}
-              | {min_heap_size, Size :: non_neg_integer()}
-              | {min_bin_vheap_size, VSize :: non_neg_integer()}.
+      Options :: [spawn_opt_option()].
 spawn_opt(F, O) when erlang:is_function(F) ->
     spawn_opt(erlang, apply, [F, []], O);
 spawn_opt({M,F}=MF, O) when erlang:is_atom(M), erlang:is_atom(F) ->
@@ -2573,12 +2584,7 @@ spawn_opt(F, O) ->
 -spec spawn_opt(Node, Fun, Options) -> pid() | {pid(), reference()} when
       Node :: node(),
       Fun :: function(),
-      Options :: [Option],
-      Option :: link | monitor
-              | {priority, Level :: priority_level()}
-              | {fullsweep_after, Number :: non_neg_integer()}
-              | {min_heap_size, Size :: non_neg_integer()}
-              | {min_bin_vheap_size, VSize :: non_neg_integer()}.
+      Options :: [spawn_opt_option()].
 spawn_opt(N, F, O) when N =:= erlang:node() ->
     spawn_opt(F, O);
 spawn_opt(N, F, O) when erlang:is_function(F) ->
@@ -2665,12 +2671,7 @@ spawn_link(N,M,F,A) ->
       Module :: module(),
       Function :: atom(),
       Args :: [term()],
-      Options :: [Option],
-      Option :: link | monitor
-              | {priority, Level :: priority_level()}
-              | {fullsweep_after, Number :: non_neg_integer()}
-              | {min_heap_size, Size :: non_neg_integer()}
-              | {min_bin_vheap_size, VSize :: non_neg_integer()}.
+      Options :: [spawn_opt_option()].
 spawn_opt(M, F, A, Opts) ->
     case catch erlang:spawn_opt({M,F,A,Opts}) of
 	{'EXIT',{Reason,_}} ->
@@ -2685,12 +2686,7 @@ spawn_opt(M, F, A, Opts) ->
       Module :: module(),
       Function :: atom(),
       Args :: [term()],
-      Options :: [Option],
-      Option :: link | monitor
-              | {priority, Level :: priority_level()}
-              | {fullsweep_after, Number :: non_neg_integer()}
-              | {min_heap_size, Size :: non_neg_integer()}
-              | {min_bin_vheap_size, VSize :: non_neg_integer()}.
+      Options :: [spawn_opt_option()].
 spawn_opt(N, M, F, A, O) when N =:= erlang:node(),
 			      erlang:is_atom(M), erlang:is_atom(F),
                               erlang:is_list(A), erlang:is_list(O) ->