Index: llvm/lib/Transforms/Utils/LCSSA.cpp
===================================================================
--- llvm/lib/Transforms/Utils/LCSSA.cpp
+++ llvm/lib/Transforms/Utils/LCSSA.cpp
@@ -197,6 +197,16 @@
         continue;
       }
 
+      // If we added a single PHI, it must dominate all uses and we can directly
+      // rename it.
+      if (AddedPHIs.size() == 1) {
+        // Tell the VHs that the uses changed. This updates SCEV's caches.
+        if (UseToRewrite->get()->hasValueHandle())
+          ValueHandleBase::ValueIsRAUWd(*UseToRewrite, AddedPHIs[0]);
+        UseToRewrite->set(AddedPHIs[0]);
+        continue;
+      }
+
       // Otherwise, do full PHI insertion.
       SSAUpdate.RewriteUse(*UseToRewrite);
     }
@@ -212,8 +222,9 @@
         continue;
       // We currently only handle debug values residing in blocks where we have
       // inserted a PHI instruction.
-      if (Value *V = SSAUpdate.FindValueForBlock(UserBB))
-        DVI->setOperand(0, MetadataAsValue::get(Ctx, ValueAsMetadata::get(V)));
+      Value *V = AddedPHIs.size() == 1 ? AddedPHIs[0]
+                                       : SSAUpdate.FindValueForBlock(UserBB);
+      DVI->setOperand(0, MetadataAsValue::get(Ctx, ValueAsMetadata::get(V)));
     }
 
     // SSAUpdater might have inserted phi-nodes inside other loops. We'll need