diff --git a/llvm/lib/Support/regex_impl.h b/llvm/lib/Support/regex_impl.h
--- a/llvm/lib/Support/regex_impl.h
+++ b/llvm/lib/Support/regex_impl.h
@@ -35,8 +35,8 @@
  *	@(#)regex.h	8.1 (Berkeley) 6/2/93
  */
 
-#ifndef _REGEX_H_
-#define	_REGEX_H_
+#ifndef LLVM_SUPPORT_REGEX_IMPL_H
+#define LLVM_SUPPORT_REGEX_IMPL_H
 
 #include <sys/types.h>
 typedef off_t llvm_regoff_t;
@@ -105,4 +105,4 @@
 }
 #endif
 
-#endif /* !_REGEX_H_ */
+#endif /* LLVM_SUPPORT_REGEX_IMPL_H */