Index: lib/asan/asan_flags.inc
===================================================================
--- lib/asan/asan_flags.inc
+++ lib/asan/asan_flags.inc
@@ -75,10 +75,6 @@
           "295.*.")
 ASAN_FLAG(bool, unmap_shadow_on_exit, false,
           "If set, explicitly unmaps the (huge) shadow at exit.")
-ASAN_FLAG(
-    bool, abort_on_error, SANITIZER_MAC,
-    "If set, the tool calls abort() instead of _exit() after printing the "
-    "error report.")
 ASAN_FLAG(bool, print_stats, false,
           "Print various statistics after printing an error message or if "
           "atexit=1.")
Index: lib/asan/asan_rtl.cc
===================================================================
--- lib/asan/asan_rtl.cc
+++ lib/asan/asan_rtl.cc
@@ -56,8 +56,6 @@
       UnmapOrDie((void*)kLowShadowBeg, kHighShadowEnd - kLowShadowBeg);
     }
   }
-  if (flags()->abort_on_error)
-    Abort();
 }
 
 static void AsanCheckFailed(const char *file, int line, const char *cond,
Index: lib/sanitizer_common/sanitizer_common.cc
===================================================================
--- lib/sanitizer_common/sanitizer_common.cc
+++ lib/sanitizer_common/sanitizer_common.cc
@@ -142,6 +142,8 @@
     if (InternalDieCallbacks[i])
       InternalDieCallbacks[i]();
   }
+  if (common_flags()->abort_on_error)
+    Abort();
   internal__exit(common_flags()->exitcode);
 }
 
Index: lib/sanitizer_common/sanitizer_common_nolibc.cc
===================================================================
--- lib/sanitizer_common/sanitizer_common_nolibc.cc
+++ lib/sanitizer_common/sanitizer_common_nolibc.cc
@@ -13,6 +13,7 @@
 
 #include "sanitizer_platform.h"
 #include "sanitizer_common.h"
+#include "sanitizer_libc.h"
 
 namespace __sanitizer {
 
@@ -20,4 +21,6 @@
 void WriteToSyslog(const char *buffer) {}
 #endif
 
-}
+void Abort() { internal__exit(1); }
+
+}  // namespace __sanitizer
Index: lib/sanitizer_common/sanitizer_flags.inc
===================================================================
--- lib/sanitizer_common/sanitizer_flags.inc
+++ lib/sanitizer_common/sanitizer_flags.inc
@@ -187,3 +187,7 @@
                                              "user-readable names")
 COMMON_FLAG(int, exitcode, 1, "Override the program exit status if the tool "
                               "found an error")
+COMMON_FLAG(
+    bool, abort_on_error, SANITIZER_MAC,
+    "If set, the tool calls abort() instead of _exit() after printing the "
+    "error report.")
Index: test/sanitizer_common/TestCases/Darwin/abort_on_error.cc
===================================================================
--- /dev/null
+++ test/sanitizer_common/TestCases/Darwin/abort_on_error.cc
@@ -0,0 +1,19 @@
+// Check that sanitizers on OS X crash the process by default (i.e.
+// abort_on_error=1). See also Linux/abort_on_error.cc.
+
+// RUN: %clangxx %s -o %t
+
+// Intentionally don't inherit the default options.
+// RUN: %env_tool_opts='' not --crash %run %t 2>&1
+
+// When we use lit's default options, we shouldn't crash.
+// RUN: not %run %t 2>&1
+
+int global;
+
+int main() {
+  volatile int *a = new int[100];
+  delete[] a;
+  global = a[0];  // use-after-free: triggers ASan report.
+  return 0;
+}
Index: test/sanitizer_common/TestCases/Darwin/lit.local.cfg
===================================================================
--- /dev/null
+++ test/sanitizer_common/TestCases/Darwin/lit.local.cfg
@@ -0,0 +1,9 @@
+def getRoot(config):
+  if not config.parent:
+    return config
+  return getRoot(config.parent)
+
+root = getRoot(config)
+
+if root.host_os not in ['Darwin']:
+  config.unsupported = True
Index: test/sanitizer_common/TestCases/Linux/abort_on_error.cc
===================================================================
--- /dev/null
+++ test/sanitizer_common/TestCases/Linux/abort_on_error.cc
@@ -0,0 +1,20 @@
+// Check that sanitizers call _exit() on Linux by default (i.e.
+// abort_on_error=0). See also Darwin/abort_on_error.cc.
+
+// RUN: %clangxx %s -o %t
+
+// Intentionally don't inherit the default options.
+// RUN: %env_tool_opts='' not %run %t 2>&1
+
+// When we use lit's default options, we shouldn't crash either. On Linux
+// lit doesn't set options anyway.
+// RUN: not %run %t 2>&1
+
+namespace __sanitizer {
+void Die();
+}
+
+int main() {
+  __sanitizer::Die();
+  return 0;
+}
Index: test/sanitizer_common/lit.common.cfg
===================================================================
--- test/sanitizer_common/lit.common.cfg
+++ test/sanitizer_common/lit.common.cfg
@@ -5,6 +5,7 @@
 
 config.name = "SanitizerCommon-" + config.tool_name
 
+default_tool_options = []
 if config.tool_name == "asan":
   tool_cflags = ["-fsanitize=address"]
   tool_options = "ASAN_OPTIONS"
@@ -22,6 +23,15 @@
 
 config.available_features.add(config.tool_name)
 
+if config.host_os == 'Darwin':
+  # On Darwin, we default to `abort_on_error=1`, which would make tests run
+  # much slower. Let's override this and run lit tests with 'abort_on_error=0'.
+  default_tool_options += ['abort_on_error=0']
+default_tool_options_str = ':'.join(default_tool_options)
+if default_tool_options_str:
+  config.environment[tool_options] = default_tool_options_str
+  default_tool_options_str += ':'
+
 clang_cflags = config.debug_info_flags + tool_cflags + [config.target_cflags]
 clang_cxxflags = config.cxx_mode_flags + clang_cflags
 
@@ -31,7 +41,6 @@
 config.substitutions.append( ("%clang ", build_invocation(clang_cflags)) )
 config.substitutions.append( ("%clangxx ", build_invocation(clang_cxxflags)) )
 config.substitutions.append( ("%tool_name", config.tool_name) )
-default_tool_options_str = ''
 config.substitutions.append( ('%env_tool_opts=',
                               'env ' + tool_options + '=' + default_tool_options_str))
 
Index: test/ubsan/lit.common.cfg
===================================================================
--- test/ubsan/lit.common.cfg
+++ test/ubsan/lit.common.cfg
@@ -14,6 +14,7 @@
 # Setup source root.
 config.test_source_root = os.path.dirname(__file__)
 
+default_ubsan_opts = []
 # Choose between standalone and UBSan+ASan modes.
 ubsan_lit_test_mode = get_required_attr(config, 'ubsan_lit_test_mode')
 if ubsan_lit_test_mode == "Standalone":
@@ -24,13 +25,7 @@
   config.name = 'UBSan-ASan-' + config.target_arch
   config.available_features.add("ubsan-asan")
   clang_ubsan_cflags = ["-fsanitize=address"]
-  config.environment['ASAN_OPTIONS'] = 'detect_leaks=0'
-  
-  # Platform-specific default ASAN_OPTIONS for lit tests.
-  if config.host_os == 'Darwin':
-    # On Darwin, we default to `abort_on_error=1`, which would make tests run
-    # much slower. Let's override this and run lit tests with 'abort_on_error=0'.
-    config.environment['ASAN_OPTIONS'] = 'abort_on_error=0'
+  default_ubsan_opts += ['detect_leaks=0']
 elif ubsan_lit_test_mode == "MemorySanitizer":
   config.name = 'UBSan-MSan-' + config.target_arch
   config.available_features.add("ubsan-msan")
@@ -42,9 +37,18 @@
 else:
   lit_config.fatal("Unknown UBSan test mode: %r" % ubsan_lit_test_mode)
 
+# Platform-specific default for lit tests.
+if config.host_os == 'Darwin':
+  # On Darwin, we default to `abort_on_error=1`, which would make tests run
+  # much slower. Let's override this and run lit tests with 'abort_on_error=0'.
+  default_ubsan_opts += ['abort_on_error=0']
+default_ubsan_opts_str = ':'.join(default_ubsan_opts)
+if default_ubsan_opts_str:
+  config.environment['UBSAN_OPTIONS'] = default_ubsan_opts_str
+  default_ubsan_opts_str += ':'
 # Substitution to setup UBSAN_OPTIONS in portable way.
 config.substitutions.append(('%env_ubsan_opts=',
-                             'env UBSAN_OPTIONS='))
+                             'env UBSAN_OPTIONS=' + default_ubsan_opts_str))
 
 def build_invocation(compile_flags):
   return " " + " ".join([config.clang] + compile_flags) + " "