Index: lib/asan/asan_flags.h
===================================================================
--- lib/asan/asan_flags.h
+++ lib/asan/asan_flags.h
@@ -27,6 +27,10 @@
 // 4) overriden from env variable ASAN_OPTIONS.
 // 5) overriden during ASan activation (for now used on Android only).
 
+#if SANITIZER_MAC
+#define ASAN_DEFAULT_OPTIONS abort_on_error=1
+#endif
+
 namespace __asan {
 
 struct Flags {
Index: test/asan/TestCases/Darwin/abort_on_error-darwin.cc
===================================================================
--- test/asan/TestCases/Darwin/abort_on_error-darwin.cc
+++ test/asan/TestCases/Darwin/abort_on_error-darwin.cc
@@ -0,0 +1,16 @@
+// Check that with empty ASAN_OPTIONS, ASan reports on OS X actually crash
+// the process (abort_on_error=1). See also Linux/abort_on_error-linux.cc.
+
+// RUN: %clangxx_asan %s -o %t
+
+// Intentionally don't inherit the default ASAN_OPTIONS.
+// RUN: ASAN_OPTIONS="" not --crash %run %t 2>&1 | FileCheck %s
+
+#include <stdlib.h>
+int main() {
+  char *x = (char*)malloc(10 * sizeof(char));
+  free(x);
+  return x[5];
+  // CHECK: {{.*ERROR: AddressSanitizer: heap-use-after-free on address}}
+  // CHECK:   {{0x.* at pc 0x.* bp 0x.* sp 0x.*}}
+}
Index: test/asan/TestCases/Linux/abort_on_error-linux.cc
===================================================================
--- test/asan/TestCases/Linux/abort_on_error-linux.cc
+++ test/asan/TestCases/Linux/abort_on_error-linux.cc
@@ -0,0 +1,16 @@
+// Check that with empty ASAN_OPTIONS, ASan reports on Linux don't crash
+// the process (abort_on_error=0). See also Darwin/abort_on_error-darwin.cc.
+
+// RUN: %clangxx_asan %s -o %t
+
+// Intentionally don't inherit the default ASAN_OPTIONS.
+// RUN: ASAN_OPTIONS="" not run %t 2>&1 | FileCheck %s
+
+#include <stdlib.h>
+int main() {
+  char *x = (char*)malloc(10 * sizeof(char));
+  free(x);
+  return x[5];
+  // CHECK: {{.*ERROR: AddressSanitizer: heap-use-after-free on address}}
+  // CHECK:   {{0x.* at pc 0x.* bp 0x.* sp 0x.*}}
+}
Index: test/asan/lit.cfg
===================================================================
--- test/asan/lit.cfg
+++ test/asan/lit.cfg
@@ -150,6 +150,7 @@
 
 if config.host_os == 'Darwin':
   config.suffixes.append('.mm')
+  config.environment["ASAN_OPTIONS"] = "abort_on_error=0"
 
 # AddressSanitizer tests are currently supported on Linux, Darwin and
 # FreeBSD only.