diff --git a/clang/lib/Parse/ParsePragma.cpp b/clang/lib/Parse/ParsePragma.cpp
index aa915fa3ba1c..abddb6ba6704 100644
--- a/clang/lib/Parse/ParsePragma.cpp
+++ b/clang/lib/Parse/ParsePragma.cpp
@@ -1014,6 +1014,8 @@ static bool isAbstractAttrMatcherRule(attr::SubjectMatchRule Rule) {
     return IsAbstract;
 #include "clang/Basic/AttrSubMatchRulesList.inc"
   }
+  llvm_unreachable("Invalid attribute subject match rule");
+  return false;
 }
 
 static void diagnoseExpectedAttributeSubjectSubRule(
diff --git a/clang/utils/TableGen/ClangAttrEmitter.cpp b/clang/utils/TableGen/ClangAttrEmitter.cpp
index 7aa8bdc781e8..65dbccde62c3 100644
--- a/clang/utils/TableGen/ClangAttrEmitter.cpp
+++ b/clang/utils/TableGen/ClangAttrEmitter.cpp
@@ -3168,7 +3168,7 @@ emitAttributeMatchRules(PragmaClangAttributeSupport &PragmaAttributeSupport,
     OS << ";\n";
   }
   OS << "  }\n";
-  OS << "  llvm_unreachable(\"Invalid match rule\");\n";
+  OS << "  llvm_unreachable(\"Invalid match rule\");\nreturn false;\n";
   OS << "}\n\n";
 }