diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 245fe1f5f2..6bb5b6c3a0 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -9,6 +9,7 @@ set(CLANG_TEST_DIRECTORIES
   "Driver"
   "FixIt"
   "Frontend"
+  "Headers"
   "Index"
   "Lexer"
   "Misc"
diff --git a/test/Headers/typedef_guards.c b/test/Headers/typedef_guards.c
new file mode 100644
index 0000000000..1aa667bb7e
--- /dev/null
+++ b/test/Headers/typedef_guards.c
@@ -0,0 +1,28 @@
+// RUN: %clang -fsyntax-only -verify %s
+
+// NULL is rdefined in stddef.h
+#define NULL ((void*) 0)
+
+// These are headers bundled with Clang.
+#include <stdarg.h>
+#include <stddef.h>
+
+#ifndef _VA_LIST
+typedef __builtin_va_list va_list;
+#endif
+
+#ifndef _SIZE_T
+typedef __typeof__(sizeof(int)) size_t;
+#endif
+
+#ifndef _WCHAR_T
+typedef __typeof__(*L"") wchar_t;
+#endif
+
+extern void foo(wchar_t x);
+extern void bar(size_t x);
+void *baz() { return NULL; }
+void quz() {
+  va_list y;
+}
+