Index: lib/Basic/Targets.cpp
===================================================================
--- lib/Basic/Targets.cpp	(revision 155352)
+++ lib/Basic/Targets.cpp	(working copy)
@@ -365,7 +365,7 @@
     DefineStd(Builder, "unix", Opts);
     Builder.defineMacro("__ELF__");
     if (Opts.POSIXThreads)
-      Builder.defineMacro("_POSIX_THREADS");
+      Builder.defineMacro("_REENTRANT");
   }
 public:
   OpenBSDTargetInfo(const std::string &triple)
