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
@@ -3434,9 +3434,11 @@
         return (Style.SpaceBeforeParens != FormatStyle::SBPO_Never) ||
                spaceRequiredBeforeParens(Right);
     }
+    // Handle builtins like identifiers.
     if (Line.Type != LT_PreprocessorDirective &&
-        (Left.is(tok::identifier) || Left.isFunctionLikeKeyword() ||
-         Left.is(tok::r_paren) || Left.isSimpleTypeSpecifier()))
+        (Left.is(tok::identifier) || Left.Tok.getIdentifierInfo() ||
+         Left.isFunctionLikeKeyword() || Left.is(tok::r_paren) ||
+         Left.isSimpleTypeSpecifier()))
       return spaceRequiredBeforeParens(Right);
     return false;
   }
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
@@ -15082,6 +15082,9 @@
   // verifyFormat("X A::operator++ (T);", Space);
   verifyFormat("auto lambda = [] () { return 0; };", Space);
   verifyFormat("int x = int (y);", Space);
+  verifyFormat("#define F(...) __VA_OPT__ (__VA_ARGS__)", Space);
+  verifyFormat("__builtin_LINE ()", Space);
+  verifyFormat("__builtin_UNKNOWN ()", Space);
 
   FormatStyle SomeSpace = getLLVMStyle();
   SomeSpace.SpaceBeforeParens = FormatStyle::SBPO_NonEmptyParentheses;