Index: compiler-rt/trunk/test/tsan/lit.cfg
===================================================================
--- compiler-rt/trunk/test/tsan/lit.cfg
+++ compiler-rt/trunk/test/tsan/lit.cfg
@@ -20,6 +20,11 @@
 # Setup environment variables for running ThreadSanitizer.
 tsan_options = "atexit_sleep_ms=0"
 
+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'.
+  tsan_options += ':abort_on_error=0'
+
 config.environment['TSAN_OPTIONS'] = tsan_options
 
 # GCC driver doesn't add necessary compile/link flags with -fsanitize=thread.
@@ -34,7 +39,8 @@
                      "-m64"] + config.debug_info_flags + extra_cflags
 clang_tsan_cxxflags = config.cxx_mode_flags + clang_tsan_cflags
 # Add additional flags if we're using instrumented libc++.
-if config.has_libcxx:
+# Instrumented libcxx currently not supported on Darwin.
+if config.has_libcxx and config.host_os != 'Darwin':
   # FIXME: Dehardcode this path somehow.
   libcxx_path = os.path.join(config.compiler_rt_obj_root, "lib",
                              "tsan", "libcxx_tsan")
@@ -60,8 +66,8 @@
 # Default test suffixes.
 config.suffixes = ['.c', '.cc', '.cpp']
 
-# ThreadSanitizer tests are currently supported on FreeBSD and Linux only.
-if config.host_os not in ['FreeBSD', 'Linux']:
+# ThreadSanitizer tests are currently supported on FreeBSD, Linux and Darwin.
+if config.host_os not in ['FreeBSD', 'Linux', 'Darwin']:
   config.unsupported = True
 
 # Allow tests to use REQUIRES=stable-runtime.  For use when you cannot use XFAIL