diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index ad26719..e4f5125 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -1757,6 +1757,9 @@
     if (Res.Val != N) return Res;
   }
   
+  if (N0.getOpcode() == ISD::BIT_CONVERT)  // conv(conv(x,t1),t2) -> conv(x,t2)
+    return DAG.getNode(ISD::BIT_CONVERT, VT, N0.getOperand(0));
+  
   return SDOperand();
 }
 
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 76d983f..b510f1c 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -916,6 +916,8 @@
     assert(MVT::getSizeInBits(VT)==MVT::getSizeInBits(Operand.getValueType()) &&
            "Cannot BIT_CONVERT between two different types!");
     if (VT == Operand.getValueType()) return Operand;  // noop conversion.
+    if (OpOpcode == ISD::BIT_CONVERT)  // bitconv(bitconv(x)) -> bitconv(x)
+      return getNode(ISD::BIT_CONVERT, VT, Operand.getOperand(0));
     break;
   case ISD::FNEG:
     if (OpOpcode == ISD::FSUB)   // -(X-Y) -> (Y-X)