Index: lib/Transforms/Utils/CloneFunction.cpp
===================================================================
--- lib/Transforms/Utils/CloneFunction.cpp
+++ lib/Transforms/Utils/CloneFunction.cpp
@@ -688,13 +688,19 @@
     // Update LoopInfo.
     NewLoop->addBasicBlockToLoop(NewBB, *LI);
 
-    // Update DominatorTree.
-    BasicBlock *IDomBB = DT->getNode(BB)->getIDom()->getBlock();
-    DT->addNewBlock(NewBB, cast<BasicBlock>(VMap[IDomBB]));
+    // Add DominatorTree node. After seeing all blocks, update to correct IDom.
+    DT->addNewBlock(NewBB, NewPH);
 
     Blocks.push_back(NewBB);
   }
 
+  for (BasicBlock *BB : OrigLoop->getBlocks()) {
+    // Update DominatorTree.
+    BasicBlock *IDomBB = DT->getNode(BB)->getIDom()->getBlock();
+    DT->changeImmediateDominator(cast<BasicBlock>(VMap[BB]),
+                                 cast<BasicBlock>(VMap[IDomBB]));
+  }
+
   // Move them physically from the end of the block list.
   F->getBasicBlockList().splice(Before->getIterator(), F->getBasicBlockList(),
                                 NewPH);