diff --git a/llvm/lib/Analysis/MemorySSAUpdater.cpp b/llvm/lib/Analysis/MemorySSAUpdater.cpp
--- a/llvm/lib/Analysis/MemorySSAUpdater.cpp
+++ b/llvm/lib/Analysis/MemorySSAUpdater.cpp
@@ -792,20 +792,8 @@
       DeleteUpdates.push_back({DT.Delete, Update.getFrom(), Update.getTo()});
   }
 
-  if (!DeleteUpdates.empty()) {
-    // Update for inserted edges: use newDT and snapshot CFG as if deletes had
-    // not occurred.
-    // FIXME: This creates a new DT, so it's more expensive to do mix
-    // delete/inserts vs just inserts. We can do an incremental update on the DT
-    // to revert deletes, than re-delete the edges. Teaching DT to do this, is
-    // part of a pending cleanup.
-    DominatorTree NewDT(DT, DeleteUpdates);
-    GraphDiff<BasicBlock *> GD(DeleteUpdates, /*ReverseApplyUpdates=*/true);
-    applyInsertUpdates(InsertUpdates, NewDT, &GD);
-  } else {
-    GraphDiff<BasicBlock *> GD;
-    applyInsertUpdates(InsertUpdates, DT, &GD);
-  }
+  GraphDiff<BasicBlock *> GD(DeleteUpdates, /*ReverseApplyUpdates=*/true);
+  applyInsertUpdates(InsertUpdates, DT, &GD);
 
   // Update for deleted edges
   for (auto &Update : DeleteUpdates)