diff --git a/clang/utils/TableGen/ClangDiagnosticsEmitter.cpp b/clang/utils/TableGen/ClangDiagnosticsEmitter.cpp
diff --git a/clang/utils/TableGen/TableGen.cpp b/clang/utils/TableGen/TableGen.cpp
@@ -52,7 +52,8 @@ enum ActionType {
   GenArmNeon,
   GenArmNeonSema,
   GenArmNeonTest,
-  GenAttrDocs
+  GenAttrDocs,
+  GenDiagDocs
 };
 
 namespace {
@@ -133,6 +134,8 @@ cl::opt<ActionType> Action(
                    "Generate ARM NEON tests for clang"),
         clEnumValN(GenAttrDocs, "gen-attr-docs",
                    "Generate attribute documentation"),
+        clEnumValN(GenDiagDocs, "gen-diag-docs",
+                   "Generate attribute documentation"),
         clEnumValEnd));
 
 cl::opt<std::string>
@@ -233,6 +236,9 @@ bool ClangTableGenMain(raw_ostream &OS, RecordKeeper &Records) {
   case GenAttrDocs:
     EmitClangAttrDocs(Records, OS);
     break;
+  case GenDiagDocs:
+    EmitClangDiagDocs(Records, OS);
+    break;
   }
 
   return false;

diff --git a/clang/utils/TableGen/TableGenBackends.h b/clang/utils/TableGen/TableGenBackends.h
@@ -69,6 +69,7 @@ void EmitNeonSema2(RecordKeeper &Records, raw_ostream &OS);
 void EmitNeonTest2(RecordKeeper &Records, raw_ostream &OS);
 
 void EmitClangAttrDocs(RecordKeeper &Records, raw_ostream &OS);
+void EmitClangDiagDocs(RecordKeeper &Records, raw_ostream &OS);
 
 } // end namespace clang