diff --git a/llvm/lib/Support/APInt.cpp b/llvm/lib/Support/APInt.cpp
index 88f9ac6..6bbe9ab 100644
--- a/llvm/lib/Support/APInt.cpp
+++ b/llvm/lib/Support/APInt.cpp
@@ -483,6 +483,7 @@
 }
 
 bool APInt::operator[](unsigned bitPosition) const {
+  assert(bitPosition < getBitWidth() && "Bit position out of bounds!");
   return (maskBit(bitPosition) &
           (isSingleWord() ?  VAL : pVal[whichWord(bitPosition)])) != 0;
 }