diff --git a/lib/Sema/SemaChecking.cpp b/lib/Sema/SemaChecking.cpp
index 05c726d..60ceaae 100644
--- a/lib/Sema/SemaChecking.cpp
+++ b/lib/Sema/SemaChecking.cpp
@@ -1570,6 +1570,14 @@ void Sema::CheckPrintfScanfArguments(Expr **Args, unsigned NumArgs,
                              format_idx, firstDataArg, Type))
     return;  // Literal format string found, check done!
 
+  // Do not emit diag when the string param is a macro expansion and the
+  // format is either NSString or CFString. This is a hack to prevent
+  // diag when using the NSLocalizedString and CFCopyLocalizedString macros
+  // which are usually used in place of NS and CF string literals.
+  if ((Type == "NSString" || Type == "CFString") &&
+      Args[format_idx]->getLocStart().isMacroID())
+    return;
+
   // If there are no arguments specified, warn with -Wformat-security, otherwise
   // warn only with -Wformat-nonliteral.
   if (NumArgs == format_idx+1)
diff --git a/test/SemaObjC/format-strings-objc.m b/test/SemaObjC/format-strings-objc.m
index 3fb7c9e..078bd52 100644
--- a/test/SemaObjC/format-strings-objc.m
+++ b/test/SemaObjC/format-strings-objc.m
@@ -82,3 +82,11 @@ void check_method() {
   [Foo fooWithFormat:@"%@"]; // expected-warning {{more '%' conversions than data arguments}}
   [Foo fooWithCStringFormat:"%@"]; // expected-warning {{invalid conversion specifier '@'}}
 }
+
+// Do not emit warnings when using NSLocalizedString
+extern NSString *GetLocalizedString(NSString *str);
+#define NSLocalizedString(key) GetLocalizedString(key)
+
+void check_NSLocalizedString() {
+  [Foo fooWithFormat:NSLocalizedString(@"format"), @"arg"]; // no-warning
+}