Index: test/atomics/libcpp-has-no-threads.pass.cpp
===================================================================
--- test/atomics/libcpp-has-no-threads.pass.cpp
+++ test/atomics/libcpp-has-no-threads.pass.cpp
@@ -0,0 +1,20 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+// XFAIL: libcpp-has-no-threads
+
+int main()
+{
+  // Together with the XFAIL above, ensure that libcpp-has-no-threads is set as
+  // a LIT feature iff _LIBCPP_HAS_NO_THREADS is defined:
+#ifdef _LIBCPP_HAS_NO_THREADS
+  return -1;
+#else
+  return 0;
+#endif
+}