Index: lib/sanitizer_common/sanitizer_symbolizer_internal.h
===================================================================
--- lib/sanitizer_common/sanitizer_symbolizer_internal.h
+++ lib/sanitizer_common/sanitizer_symbolizer_internal.h
@@ -28,6 +28,8 @@
 const char *ExtractTokenUpToDelimiter(const char *str, const char *delimiter,
                                       char **result);
 
+const char *DemangleCXXABI(const char *name);
+
 // SymbolizerTool is an interface that is implemented by individual "tools"
 // that can perform symbolication (external llvm-symbolizer, libbacktrace,
 // Windows DbgHelp symbolizer, etc.).
Index: lib/sanitizer_common/sanitizer_symbolizer_mac.cc
===================================================================
--- lib/sanitizer_common/sanitizer_symbolizer_mac.cc
+++ lib/sanitizer_common/sanitizer_symbolizer_mac.cc
@@ -31,7 +31,11 @@
   Dl_info info;
   int result = dladdr((const void *)addr, &info);
   if (!result) return false;
-  stack->info.function = internal_strdup(info.dli_sname);
+  if (const char *demangled = DemangleCXXABI(info.dli_sname)) {
+    stack->info.function = internal_strdup(demangled);
+  } else {
+    stack->info.function = internal_strdup(info.dli_sname);
+  }
   return true;
 }
 
Index: lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cc
===================================================================
--- lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cc
+++ lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cc
@@ -38,7 +38,7 @@
 namespace __sanitizer {
 
 // Attempts to demangle the name via __cxa_demangle from __cxxabiv1.
-static const char *DemangleCXXABI(const char *name) {
+const char *DemangleCXXABI(const char *name) {
   // FIXME: __cxa_demangle aggressively insists on allocating memory.
   // There's not much we can do about that, short of providing our
   // own demangler (libc++abi's implementation could be adapted so that
Index: test/asan/TestCases/Darwin/dladdr-demangling.cc
===================================================================
--- test/asan/TestCases/Darwin/dladdr-demangling.cc
+++ test/asan/TestCases/Darwin/dladdr-demangling.cc
@@ -0,0 +1,33 @@
+// In a non-forking sandbox, we fallback to dladdr(). Test that we provide
+// properly demangled C++ names in that case.
+
+// RUN: %clangxx_asan -O0 %s -o %t 
+// RUN: not %run %t 2>&1 | FileCheck %s
+// RUN: ASAN_OPTIONS=verbosity=2 not %run sandbox-exec -p '(version 1)(allow default)(deny process-fork)' %t 2>&1 | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-DLADDR
+
+#include <stdlib.h>
+
+class MyClass {
+ public:
+  int my_function(int n) {
+    char *x = (char*)malloc(n * sizeof(char));
+    free(x);
+    return x[5];
+    // CHECK: {{.*ERROR: AddressSanitizer: heap-use-after-free on address}}
+    // CHECK: {{READ of size 1 at 0x.* thread T0}}
+    // CHECK-DLADDR: Using dladdr symbolizer as fallback
+    // CHECK-DLADDR: failed to fork external symbolizer
+    // CHECK: {{    #0 0x.* in MyClass::my_function\(int\)}}
+    // CHECK: {{freed by thread T0 here:}}
+    // CHECK: {{    #0 0x.* in wrap_free}}
+    // CHECK: {{    #1 0x.* in MyClass::my_function\(int\)}}
+    // CHECK: {{previously allocated by thread T0 here:}}
+    // CHECK: {{    #0 0x.* in wrap_malloc}}
+    // CHECK: {{    #1 0x.* in MyClass::my_function\(int\)}}
+  }
+};
+
+int main() {
+  MyClass o;
+  return o.my_function(10);
+}