diff --git a/llvm/lib/Transforms/IPO/AttributorAttributes.cpp b/llvm/lib/Transforms/IPO/AttributorAttributes.cpp
--- a/llvm/lib/Transforms/IPO/AttributorAttributes.cpp
+++ b/llvm/lib/Transforms/IPO/AttributorAttributes.cpp
@@ -7781,6 +7781,10 @@
 
   /// See AbstractAttribute::initialize(...).
   void initialize(Attributor &A) override {
+    if (getIRPosition().hasAttr({Attribute::NoUndef})) {
+      indicateOptimisticFixpoint();
+      return;
+    }
     Value &V = getAssociatedValue();
     if (isa<UndefValue>(V))
       indicatePessimisticFixpoint();