diff --git a/llvm/lib/Transforms/Utils/LowerSwitch.cpp b/llvm/lib/Transforms/Utils/LowerSwitch.cpp
index e25956299c65..35cd917330ab 100644
--- a/llvm/lib/Transforms/Utils/LowerSwitch.cpp
+++ b/llvm/lib/Transforms/Utils/LowerSwitch.cpp
@@ -149,6 +149,7 @@ static void fixPhis(BasicBlock *SuccBB, BasicBlock *OrigBB, BasicBlock *NewBB,
 
     // Only update the first occurence.
     unsigned Idx = 0, E = PN->getNumIncomingValues();
+    unsigned LocalNumMergedCases = NumMergedCases;
     for (; Idx != E; ++Idx) {
       if (PN->getIncomingBlock(Idx) == OrigBB) {
         PN->setIncomingBlock(Idx, NewBB);
@@ -158,10 +159,10 @@ static void fixPhis(BasicBlock *SuccBB, BasicBlock *OrigBB, BasicBlock *NewBB,
 
     // Remove additional occurences coming from condensed cases and keep the
     // number of incoming values equal to the number of branches to SuccBB.
-    for (++Idx; NumMergedCases > 0 && Idx != E; ++Idx)
+    for (++Idx; LocalNumMergedCases > 0 && Idx < E; ++Idx)
       if (PN->getIncomingBlock(Idx) == OrigBB) {
         PN->removeIncomingValue(Idx);
-        NumMergedCases--;
+        LocalNumMergedCases--;
       }
   }
 }
diff --git a/llvm/test/Transforms/Util/lowerswitch.ll b/llvm/test/Transforms/Util/lowerswitch.ll
index adbfbda90167..17c12028705f 100644
--- a/llvm/test/Transforms/Util/lowerswitch.ll
+++ b/llvm/test/Transforms/Util/lowerswitch.ll
@@ -45,6 +45,8 @@ bb3:
 ; CHECK-LABEL: bb3
 ; CHECK: %tmp = phi i32 [ 1, %NodeBlock ], [ 0, %bb2 ], [ 1, %LeafBlock3 ]
   %tmp = phi i32 [ 1, %bb1 ], [ 0, %bb2 ], [ 1, %bb1 ], [ 1, %bb1 ]
+; CHECK-NEXT: %tmp2 = phi i32 [ 2, %NodeBlock ], [ 5, %bb2 ], [ 2, %LeafBlock3 ]
+  %tmp2 = phi i32 [ 2, %bb1 ], [ 2, %bb1 ], [ 5, %bb2 ], [ 2, %bb1 ]
   br label %exit
 
 exit: