diff --git a/clang/lib/Format/TokenAnnotator.cpp b/clang/lib/Format/TokenAnnotator.cpp
--- a/clang/lib/Format/TokenAnnotator.cpp
+++ b/clang/lib/Format/TokenAnnotator.cpp
@@ -3888,7 +3888,7 @@
 
   if (Right.is(tok::kw___attribute) ||
       (Right.is(tok::l_square) && Right.is(TT_AttributeSquare)))
-    return true;
+    return !Left.is(TT_AttributeSquare);
 
   if (Left.is(tok::identifier) && Right.is(tok::string_literal))
     return true;
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -7672,6 +7672,19 @@
                MultiLineFunctions);
 }
 
+TEST_F(FormatTest, AttributePenaltyBreaking) {
+  FormatStyle Style = getLLVMStyle();
+  verifyFormat("void ABCDEFGH::ABCDEFGHIJKLMN(\n"
+               "    [[maybe_unused]] const shared_ptr<ALongTypeName> &C d) {}",
+               Style);
+  verifyFormat("void ABCDEFGH::ABCDEFGHIJK(\n"
+               "    [[maybe_unused]] const shared_ptr<ALongTypeName> &C d) {}",
+               Style);
+  verifyFormat("void ABCDEFGH::ABCDEFGH([[maybe_unused]] const "
+               "shared_ptr<ALongTypeName> &C d) {\n}",
+               Style);
+}
+
 TEST_F(FormatTest, UnderstandsEllipsis) {
   verifyFormat("int printf(const char *fmt, ...);");
   verifyFormat("template <class... Ts> void Foo(Ts... ts) { Foo(ts...); }");