Check in LLVM r95781.
diff --git a/test/Sema/implicit-def.c b/test/Sema/implicit-def.c
new file mode 100644
index 0000000..6caa090
--- /dev/null
+++ b/test/Sema/implicit-def.c
@@ -0,0 +1,8 @@
+/* RUN: %clang_cc1 -fsyntax-only %s -std=c89
+ * RUN: not %clang_cc1 -fsyntax-only %s -std=c99 -pedantic-errors
+ */
+
+int A() {
+  return X();
+}
+