Index: llvm/lib/IR/AutoUpgrade.cpp
===================================================================
--- llvm/lib/IR/AutoUpgrade.cpp
+++ llvm/lib/IR/AutoUpgrade.cpp
@@ -915,21 +915,21 @@
 
     break;
   }
-  case 'c': {
-    if (Name.startswith("ctlz.") && F->arg_size() == 1) {
-      rename(F);
-      NewFn = Intrinsic::getDeclaration(F->getParent(), Intrinsic::ctlz,
-                                        F->arg_begin()->getType());
-      return true;
-    }
-    if (Name.startswith("cttz.") && F->arg_size() == 1) {
-      rename(F);
-      NewFn = Intrinsic::getDeclaration(F->getParent(), Intrinsic::cttz,
-                                        F->arg_begin()->getType());
-      return true;
+  case 'c':
+    // cttz & ctlz intrinsics had another argument added.
+    if (F->arg_size() == 1) {
+      Intrinsic::ID ID = StringSwitch<Intrinsic::ID>(Name)
+                             .StartsWith("ctlz.", Intrinsic::ctlz)
+                             .StartsWith("cttz.", Intrinsic::cttz)
+                             .Default(Intrinsic::not_intrinsic);
+      if (ID != Intrinsic::not_intrinsic) {
+        rename(F);
+        NewFn = Intrinsic::getDeclaration(F->getParent(), ID,
+                                          F->arg_begin()->getType());
+        return true;
+      }
     }
     break;
-  }
   case 'd':
     if (Name.consume_front("dbg.")) {
       if (Name == "addr" || (Name == "value" && F->arg_size() == 4)) {