Index: llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
===================================================================
--- llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -3457,6 +3457,12 @@
     Tmp = cast<VTSDNode>(Op.getOperand(1))->getVT().getSizeInBits();
     return VTBits-Tmp;
 
+  case ISD::BUILD_PAIR:
+    Tmp = ComputeNumSignBits(Op.getOperand(1), Depth + 1);
+    if (Op.getOperand(1).getValueSizeInBits() == Tmp)
+      Tmp += ComputeNumSignBits(Op.getOperand(0), Depth + 1);
+    return Tmp;
+
   case ISD::BUILD_VECTOR:
     Tmp = VTBits;
     for (unsigned i = 0, e = Op.getNumOperands(); (i < e) && (Tmp > 1); ++i) {