Index: clang/lib/Format/TokenAnnotator.cpp
===================================================================
--- clang/lib/Format/TokenAnnotator.cpp
+++ clang/lib/Format/TokenAnnotator.cpp
@@ -3832,6 +3832,10 @@
       Style.AllowShortBlocksOnASingleLine == FormatStyle::SBS_Never)
     return true;
 
+  // Ensure wrapping after __attribute__((XX)) and @interface etc.
+  if (Left.is(TT_AttributeParen) && Right.is(TT_ObjCDecl))
+    return true;
+
   if (Left.is(TT_LambdaLBrace)) {
     if (IsFunctionArgument(Left) &&
         Style.AllowShortLambdasOnASingleLine == FormatStyle::SLS_Inline)
Index: clang/unittests/Format/FormatTestObjC.cpp
===================================================================
--- clang/unittests/Format/FormatTestObjC.cpp
+++ clang/unittests/Format/FormatTestObjC.cpp
@@ -1526,6 +1526,18 @@
                "  [obj func:arg2];");
 }
 
+TEST_F(FormatTestObjC, Attributes) {
+  verifyFormat("__attribute__((objc_subclassing_restricted))\n"
+               "@interface Foo\n"
+               "@end");
+  verifyFormat("__attribute__((objc_subclassing_restricted))\n"
+               "@protocol Foo\n"
+               "@end");
+  verifyFormat("__attribute__((objc_subclassing_restricted))\n"
+               "@implementation Foo\n"
+               "@end");
+}
+
 } // end namespace
 } // end namespace format
 } // end namespace clang