Index: llvm/lib/Transforms/IPO/AttributorAttributes.cpp
===================================================================
--- llvm/lib/Transforms/IPO/AttributorAttributes.cpp
+++ llvm/lib/Transforms/IPO/AttributorAttributes.cpp
@@ -7743,6 +7743,16 @@
   const std::string getAsStr() const override {
     return getAssumed() ? "noundef" : "may-undef-or-poison";
   }
+
+  ChangeStatus manifest(Attributor &A) override {
+    // We don't manifest noundef attribute for dead positions because the
+    // associated values with dead positions would be replaced with undef
+    // values.
+    if (A.isAssumedDead(getIRPosition(), nullptr, nullptr,
+                        /* CheckBBLivenessOnly */ true))
+      return ChangeStatus::UNCHANGED;
+    return AANoUndef::manifest(A);
+  }
 };
 
 struct AANoUndefFloating : public AANoUndefImpl {