diff --git a/llvm/lib/IR/ConstantRange.cpp b/llvm/lib/IR/ConstantRange.cpp
index d41914ba4a96..16def8bc5e86 100644
--- a/llvm/lib/IR/ConstantRange.cpp
+++ b/llvm/lib/IR/ConstantRange.cpp
@@ -56,6 +56,8 @@ ConstantRange::ConstantRange(APInt L, APInt U)
 
 ConstantRange ConstantRange::fromKnownBits(const KnownBits &Known,
                                            bool IsSigned) {
+  assert(!Known.hasConflict() && "Expected valid KnownBits");
+
   if (Known.isUnknown())
     return ConstantRange(Known.getBitWidth(), /* full */ true);