Index: lib/Transforms/InstCombine/InstCombineCasts.cpp
===================================================================
--- lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -1873,6 +1873,10 @@
       } else if (auto *LI = dyn_cast<LoadInst>(V)) {
         Builder->SetInsertPoint(OldPN->getIncomingBlock(j)->getTerminator());
         NewV = Builder->CreateBitCast(LI, DestTy);
+        // Builder->CreateBitCast implicitly add NewV to Instruction Combiner
+        // Worklist.  This potentially leads to internal loop.  Therefore
+        // do not continue analysis of newly added BitCast Instruction.
+        Worklist.Remove(cast<Instruction>(NewV));
         Worklist.Add(LI);
       } else if (auto *BCI = dyn_cast<BitCastInst>(V)) {
         NewV = BCI->getOperand(0);
@@ -1889,7 +1893,12 @@
     auto *SI = dyn_cast<StoreInst>(U);
     if (SI && SI->isSimple() && SI->getOperand(0) == PN) {
       Builder->SetInsertPoint(SI);
-      SI->setOperand(0, Builder->CreateBitCast(NewPNodes[PN], SrcTy));
+      Value *BC = Builder->CreateBitCast(NewPNodes[PN], SrcTy);
+      SI->setOperand(0, BC);
+      // Builder->CreateBitCast implicitly add BC to Instruction Combiner
+      // Worklist.  This potentially leads to internal loop.  Therefore
+      // do not continue analysis of newly added BitCast Instruction.
+      Worklist.Remove(cast<Instruction>(BC));
       Worklist.Add(SI);
     }
   }