diff --git a/test/FrontendC/implicit-arg.c b/test/FrontendC/implicit-arg.c
new file mode 100644
index 00000000000..971245f3bad
--- /dev/null
+++ b/test/FrontendC/implicit-arg.c
@@ -0,0 +1,10 @@
+// RUN: %llvmgcc %s -S -emit-llvm -O0 -o -
+// RUN: %llvmgcc %s -S -emit-llvm -O1 -o -
+// rdar://6518089
+
+static int bar();
+void foo() {
+  int a = bar();
+}
+int bar(unsigned a) {
+}