diff --git a/clang/lib/Format/Format.cpp b/clang/lib/Format/Format.cpp
--- a/clang/lib/Format/Format.cpp
+++ b/clang/lib/Format/Format.cpp
@@ -2687,6 +2687,7 @@
         "CGSizeMake",
         "CGVector",
         "CGVectorMake",
+        "FOUNDATION_EXTERN",
         "NSAffineTransform",
         "NSArray",
         "NSAttributedString",
@@ -2743,6 +2744,7 @@
         "NSURLQueryItem",
         "NSUUID",
         "NSValue",
+        "NS_ASSUME_NONNULL_BEGIN",
         "UIImage",
         "UIView",
     };
diff --git a/clang/test/Format/dump-config-objc-macros.h b/clang/test/Format/dump-config-objc-macros.h
new file mode 100644
--- /dev/null
+++ b/clang/test/Format/dump-config-objc-macros.h
@@ -0,0 +1,8 @@
+// RUN: clang-format -dump-config %s | FileCheck %s
+
+// CHECK: Language: ObjC
+NS_ASSUME_NONNULL_BEGIN
+
+FOUNDATION_EXTERN int kConstant;
+
+NS_ASSUME_NONNULL_END
diff --git a/clang/unittests/Format/FormatTestObjC.cpp b/clang/unittests/Format/FormatTestObjC.cpp
--- a/clang/unittests/Format/FormatTestObjC.cpp
+++ b/clang/unittests/Format/FormatTestObjC.cpp
@@ -94,6 +94,20 @@
   ASSERT_TRUE((bool)Style);
   EXPECT_EQ(FormatStyle::LK_ObjC, Style->Language);
 
+  Style = getStyle("{}", "a.h", "none", R"objc(
+NS_ASSUME_NONNULL_BEGIN
+extern int i;
+NS_ASSUME_NONNULL_END
+)objc");
+  ASSERT_TRUE((bool)Style);
+  EXPECT_EQ(FormatStyle::LK_ObjC, Style->Language);
+
+  Style = getStyle("{}", "a.h", "none", R"objc(
+FOUNDATION_EXTERN void DoStuff(void);
+)objc");
+  ASSERT_TRUE((bool)Style);
+  EXPECT_EQ(FormatStyle::LK_ObjC, Style->Language);
+
   Style = getStyle("{}", "a.h", "none", "enum Foo {};");
   ASSERT_TRUE((bool)Style);
   EXPECT_EQ(FormatStyle::LK_Cpp, Style->Language);