diff --git a/misc/cgo/test/cgo_test.go b/misc/cgo/test/cgo_test.go
index 3b866290fe2..682e292a703 100644
--- a/misc/cgo/test/cgo_test.go
+++ b/misc/cgo/test/cgo_test.go
@@ -31,5 +31,6 @@ func TestHelpers(t *testing.T)             { testHelpers(t) }
 func TestLibgcc(t *testing.T)              { testLibgcc(t) }
 func Test1635(t *testing.T)                { test1635(t) }
 func TestPrintf(t *testing.T)              { testPrintf(t) }
+func Test4029(t *testing.T)                { test4029(t) }
 
 func BenchmarkCgoCall(b *testing.B) { benchCgoCall(b) }
diff --git a/misc/cgo/test/issue4029.go b/misc/cgo/test/issue4029.go
new file mode 100644
index 00000000000..b8a0a6d985d
--- /dev/null
+++ b/misc/cgo/test/issue4029.go
@@ -0,0 +1,57 @@
+// Copyright 2012 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package cgotest
+
+/*
+#include <dlfcn.h> 
+*/
+import "C"
+
+import (
+	"fmt"
+	"testing"
+)
+
+//export IMPIsOpaque
+func IMPIsOpaque() {
+	fmt.Println("isOpaque")
+}
+
+//export IMPInitWithFrame
+func IMPInitWithFrame() {
+	fmt.Println("IInitWithFrame")
+}
+
+//export IMPDrawRect
+func IMPDrawRect() {
+	fmt.Println("drawRect:")
+}
+
+//export IMPWindowResize
+func IMPWindowResize() {
+	fmt.Println("windowDidResize:")
+}
+
+func test4029(t *testing.T) {
+	loadThySelf(t, "IMPWindowResize")
+	loadThySelf(t, "IMPDrawRect")
+	loadThySelf(t, "IMPInitWithFrame")
+	loadThySelf(t, "IMPIsOpaque")
+}
+
+func loadThySelf(t *testing.T, symbol string) {
+	this_process := C.dlopen(nil, C.RTLD_NOW)
+	if this_process == nil {
+		t.Fatal("dlopen:", C.GoString(C.dlerror()))
+	}
+	defer C.dlclose(this_process)
+
+	symbol_address := C.dlsym(this_process, C.CString(symbol))
+	if symbol_address == nil {
+		t.Fatal("dlsym:", C.GoString(C.dlerror()))
+	} else {
+		t.Log(symbol, symbol_address)
+	}
+}
diff --git a/src/cmd/6l/asm.c b/src/cmd/6l/asm.c
index 05732d081d8..8af86066036 100644
--- a/src/cmd/6l/asm.c
+++ b/src/cmd/6l/asm.c
@@ -435,6 +435,7 @@ adddynsym(Sym *s)
 	Sym *d, *str;
 	int t;
 	char *name;
+	vlong off;
 
 	if(s->dynid >= 0)
 		return;
@@ -503,35 +504,51 @@ adddynsym(Sym *s)
 		name = s->dynimpname;
 		if(name == nil)
 			name = s->name;
-		s->dynid = d->size/16;
+		if(d->size == 0 && ndynexp > 0) { // pre-allocate for dynexps
+			symgrow(d, ndynexp*16);
+		}
+		if(s->dynid <= -100) { // pre-allocated, see cmd/ld/go.c:^sortdynexp()
+			s->dynid = -s->dynid-100;
+			off = s->dynid*16;
+		} else {
+			off = d->size;
+			s->dynid = off/16;
+		}
 		// darwin still puts _ prefixes on all C symbols
 		str = lookup(".dynstr", 0);
-		adduint32(d, str->size);
+		setuint32(d, off, str->size);
+		off += 4;
 		adduint8(str, '_');
 		addstring(str, name);
 		if(s->type == SDYNIMPORT) {
-			adduint8(d, 0x01);	// type - N_EXT - external symbol
-			adduint8(d, 0);	// section
+			setuint8(d, off, 0x01); // type - N_EXT - external symbol
+			off++;
+			setuint8(d, off, 0); // section
+			off++;
 		} else {
-			adduint8(d, 0x0f);
+			setuint8(d, off, 0x0f);
+			off++;
 			switch(s->type) {
 			default:
 			case STEXT:
-				adduint8(d, 1);
+				setuint8(d, off, 1);
 				break;
 			case SDATA:
-				adduint8(d, 2);
+				setuint8(d, off, 2);
 				break;
 			case SBSS:
-				adduint8(d, 4);
+				setuint8(d, off, 4);
 				break;
 			}
+			off++;
 		}
-		adduint16(d, 0);	// desc
+		setuint16(d, off, 0); // desc
+		off += 2;
 		if(s->type == SDYNIMPORT)
-			adduint64(d, 0);	// value
+			setuint64(d, off, 0); // value
 		else
-			addaddr(d, s);
+			setaddr(d, off, s);
+		off += 8;
 	} else if(HEADTYPE != Hwindows) {
 		diag("adddynsym: unsupported binary format");
 	}
diff --git a/src/cmd/8l/asm.c b/src/cmd/8l/asm.c
index 4d7734f046c..44cd77cbac4 100644
--- a/src/cmd/8l/asm.c
+++ b/src/cmd/8l/asm.c
@@ -416,6 +416,7 @@ adddynsym(Sym *s)
 	Sym *d, *str;
 	int t;
 	char *name;
+	vlong off;
 	
 	if(s->dynid >= 0)
 		return;
@@ -479,16 +480,51 @@ adddynsym(Sym *s)
 		name = s->dynimpname;
 		if(name == nil)
 			name = s->name;
-		s->dynid = d->size/12;
+		if(d->size == 0 && ndynexp > 0) { // pre-allocate for dynexps
+			symgrow(d, ndynexp*12);
+		}
+		if(s->dynid <= -100) { // pre-allocated, see cmd/ld/go.c:^sortdynexp()
+			s->dynid = -s->dynid-100;
+			off = s->dynid*12;
+		} else {
+			off = d->size;
+			s->dynid = off/12;
+		}
 		// darwin still puts _ prefixes on all C symbols
 		str = lookup(".dynstr", 0);
-		adduint32(d, str->size);
+		setuint32(d, off, str->size);
+		off += 4;
 		adduint8(str, '_');
 		addstring(str, name);
-		adduint8(d, 0x01);	// type - N_EXT - external symbol
-		adduint8(d, 0);	// section
-		adduint16(d, 0);	// desc
-		adduint32(d, 0);	// value
+		if(s->type == SDYNIMPORT) {
+			setuint8(d, off, 0x01); // type - N_EXT - external symbol
+			off++;
+			setuint8(d, off, 0); // section
+			off++;
+		} else {
+			setuint8(d, off, 0x0f);
+			off++;
+			switch(s->type) {
+			default:
+			case STEXT:
+				setuint8(d, off, 1);
+				break;
+			case SDATA:
+				setuint8(d, off, 2);
+				break;
+			case SBSS:
+				setuint8(d, off, 4);
+				break;
+			}
+			off++;
+		}
+		setuint16(d, off, 0); // desc
+		off += 2;
+		if(s->type == SDYNIMPORT)
+			setuint32(d, off, 0); // value
+		else
+			setaddr(d, off, s);
+		off += 4;
 	} else if(HEADTYPE != Hwindows) {
 		diag("adddynsym: unsupported binary format");
 	}
diff --git a/src/cmd/ld/data.c b/src/cmd/ld/data.c
index 4afe4b801cb..e551f729030 100644
--- a/src/cmd/ld/data.c
+++ b/src/cmd/ld/data.c
@@ -793,6 +793,33 @@ addaddr(Sym *s, Sym *t)
 	return addaddrplus(s, t, 0);
 }
 
+vlong
+setaddrplus(Sym *s, vlong off, Sym *t, int32 add)
+{
+	Reloc *r;
+
+	if(s->type == 0)
+		s->type = SDATA;
+	s->reachable = 1;
+	if(off+PtrSize > s->size) {
+		s->size = off + PtrSize;
+		symgrow(s, s->size);
+	}
+	r = addrel(s);
+	r->sym = t;
+	r->off = off;
+	r->siz = PtrSize;
+	r->type = D_ADDR;
+	r->add = add;
+	return off;
+}
+
+vlong
+setaddr(Sym *s, vlong off, Sym *t)
+{
+	return setaddrplus(s, off, t, 0);
+}
+
 vlong
 addsize(Sym *s, Sym *t)
 {
diff --git a/src/cmd/ld/go.c b/src/cmd/ld/go.c
index 28cf06b8bd2..8def9b7301b 100644
--- a/src/cmd/ld/go.c
+++ b/src/cmd/ld/go.c
@@ -932,3 +932,28 @@ importcycles(void)
 	for(p=pkgall; p; p=p->all)
 		cycle(p);
 }
+
+static int
+scmp(const void *p1, const void *p2)
+{
+	Sym *s1, *s2;
+
+	s1 = *(Sym**)p1;
+	s2 = *(Sym**)p2;
+	return strcmp(s1->dynimpname, s2->dynimpname);
+}
+void
+sortdynexp(void)
+{
+	int i;
+
+	// On Mac OS X Mountain Lion, we must sort exported symbols
+	// So we sort them here and pre-allocate dynid for them
+	// See http://golang.org/issue/4029
+	if(HEADTYPE != Hdarwin)
+		return;
+	qsort(dynexp, ndynexp, sizeof dynexp[0], scmp);
+	for(i=0; i<ndynexp; i++) {
+		dynexp[i]->dynid = -i-100; // also known to [68]l/asm.c:^adddynsym
+	}
+}
diff --git a/src/cmd/ld/lib.c b/src/cmd/ld/lib.c
index 135426473fb..8e3a8dd690f 100644
--- a/src/cmd/ld/lib.c
+++ b/src/cmd/ld/lib.c
@@ -309,6 +309,7 @@ loadlib(void)
 		debug['d'] = 1;
 	
 	importcycles();
+	sortdynexp();
 }
 
 /*
diff --git a/src/cmd/ld/lib.h b/src/cmd/ld/lib.h
index d322df5c6b4..162e16180f1 100644
--- a/src/cmd/ld/lib.h
+++ b/src/cmd/ld/lib.h
@@ -196,6 +196,8 @@ vlong	addaddr(Sym*, Sym*);
 vlong	addaddrplus(Sym*, Sym*, int32);
 vlong	addpcrelplus(Sym*, Sym*, int32);
 vlong	addsize(Sym*, Sym*);
+vlong	setaddrplus(Sym*, vlong, Sym*, int32);
+vlong	setaddr(Sym*, vlong, Sym*);
 void	setuint8(Sym*, vlong, uint8);
 void	setuint16(Sym*, vlong, uint16);
 void	setuint32(Sym*, vlong, uint32);
@@ -341,3 +343,5 @@ char*	decodetype_structfieldname(Sym*, int);
 Sym*	decodetype_structfieldtype(Sym*, int);
 vlong	decodetype_structfieldoffs(Sym*, int);
 vlong	decodetype_ifacemethodcount(Sym*);
+
+void	sortdynexp(void);