Index: llvm/lib/Transforms/IPO/Attributor.cpp
===================================================================
--- llvm/lib/Transforms/IPO/Attributor.cpp
+++ llvm/lib/Transforms/IPO/Attributor.cpp
@@ -4069,8 +4069,10 @@
     Value &V = getAnchorValue();
 
     // TODO: add other stuffs
-    if (isa<Constant>(V) || isa<UndefValue>(V))
-      indicatePessimisticFixpoint();
+    if (isa<Constant>(V) || isa<UndefValue>(V)) {
+      SimplifiedAssociatedValue = &V;
+      indicateOptimisticFixpoint();
+    }
   }
 
   /// See AbstractAttribute::updateImpl(...).