diff --git a/clang/utils/TableGen/ClangAttrEmitter.cpp b/clang/utils/TableGen/ClangAttrEmitter.cpp
index 42627f02cf35..f892626a447e 100644
--- a/clang/utils/TableGen/ClangAttrEmitter.cpp
+++ b/clang/utils/TableGen/ClangAttrEmitter.cpp
@@ -3739,7 +3739,8 @@ static void GenerateHasAttrSpellingStringSwitch(
                       : '(' + itostr(Version) + ')';
 
     if (Scope.empty() || Scope == Spelling.nameSpace()) {
-      if (TestStringMap.contains(Spelling.name()))
+      if (TestStringMap.contains(Spelling.name()) &&
+          TestStringMap[Spelling.name()] != TestStr)
         TestStringMap[Spelling.name()] += " || " + TestStr;
       else
         TestStringMap[Spelling.name()] = TestStr;