diff --git a/lib/Sema/SemaDeclAttr.cpp b/lib/Sema/SemaDeclAttr.cpp
index 88c89f21bddd602dece95bc7ea64373616fe6937..6e0dc8f4a98dcdad3a9bd2486cf07e5061f75a0e 100644
--- a/lib/Sema/SemaDeclAttr.cpp
+++ b/lib/Sema/SemaDeclAttr.cpp
@@ -3758,7 +3758,9 @@ static bool isForbiddenTypeAllowed(Sema &S, Decl *decl) {
   // Private ivars are always okay.  Unfortunately, people don't
   // always properly make their ivars private, even in system headers.
   // Plus we need to make fields okay, too.
-  if (!isa<FieldDecl>(decl) && !isa<ObjCPropertyDecl>(decl))
+  // Function declarations in sys headers will be marked unavailable.
+  if (!isa<FieldDecl>(decl) && !isa<ObjCPropertyDecl>(decl) &&
+      !isa<FunctionDecl>(decl))
     return false;
 
   // Require it to be declared in a system header.
diff --git a/test/SemaObjC/arc-unavailable-system-function.m b/test/SemaObjC/arc-unavailable-system-function.m
new file mode 100644
index 0000000000000000000000000000000000000000..d4f1095a4ad38db107cdad0e2e32cbdeade195ee
--- /dev/null
+++ b/test/SemaObjC/arc-unavailable-system-function.m
@@ -0,0 +1,13 @@
+// RUN: %clang_cc1 -fsyntax-only -triple x86_64-apple-darwin11 -fobjc-arc -fobjc-nonfragile-abi -verify %s
+// rdar://10186625
+
+# 1 "<command line>"
+# 1 "/System/Library/Frameworks/Foundation.framework/Headers/Foundation.h" 1 3
+id * foo(); // expected-note {{function has been explicitly marked unavailable here}}
+
+# 1 "arc-unavailable-system-function.m" 2
+void ret() {
+  foo(); // expected-error {{'foo' is unavailable: this system declaration uses an unsupported type}}
+}
+
+