Index: llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
===================================================================
--- llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -4048,8 +4048,11 @@
     // getOrCreateVectorValue calls below.
     Builder.SetInsertPoint(NewPhi);
 
-    // The predecessor order is preserved and we can rely on mapping between
-    // scalar and vector block predecessors.
+    // The order of predecessors can be different between OrigPhi BB and NewPhi
+    // BB. Check dominance of incoming values and map incoming value and BB
+    // according to the dominace.
+    SmallVector<Value *, 2> NewIncomingValues;
+    bool NeedSwap = false;
     for (unsigned i = 0; i < NumIncomingValues; ++i) {
       BasicBlock *NewPredBB = VectorBBPredecessors[i];
 
@@ -4060,6 +4063,23 @@
 
       // Scalar incoming value may need a broadcast
       Value *NewIncV = getOrCreateVectorValue(ScIncV, 0);
+
+      // Check dominance of NewIncV with NewPredBB.
+      if (Instruction *NewIncI = dyn_cast<Instruction>(NewIncV)) {
+        if (!DT->dominates(NewIncI, NewPredBB)) {
+          NeedSwap = true;
+        }
+      }
+      NewIncomingValues.push_back(NewIncV);
+    }
+
+    if (NeedSwap) {
+      std::swap(NewIncomingValues[0], NewIncomingValues[1]);
+    }
+
+    for (unsigned i = 0; i < NumIncomingValues; ++i) {
+      BasicBlock *NewPredBB = VectorBBPredecessors[i];
+      Value *NewIncV = NewIncomingValues[i];
       NewPhi->addIncoming(NewIncV, NewPredBB);
     }
   }