diff --git a/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp b/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
--- a/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
+++ b/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
@@ -370,7 +370,9 @@
   }
 
   if (match(V, m_NUWShl(m_Value(Op1), m_ConstantInt(CI))) && canUseSExt(CI)) {
-    int64_t Mult = int64_t(std::pow(int64_t(2), CI->getSExtValue()));
+    if (CI->getSExtValue() < 0 || CI->getSExtValue() >= 64)
+      return {V, IsKnownNonNegative};
+    int64_t Mult = 1 << CI->getSExtValue();
     auto Result = decompose(Op1, Preconditions, IsSigned, DL);
     Result.mul(Mult);
     return Result;
diff --git a/llvm/test/Transforms/ConstraintElimination/shl.ll b/llvm/test/Transforms/ConstraintElimination/shl.ll
--- a/llvm/test/Transforms/ConstraintElimination/shl.ll
+++ b/llvm/test/Transforms/ConstraintElimination/shl.ll
@@ -1232,7 +1232,7 @@
 ; CHECK:       main:
 ; CHECK-NEXT:    [[TMP0:%.*]] = shl nuw nsw i64 [[START]], -1
 ; CHECK-NEXT:    [[TMP1:%.*]] = icmp uge i64 [[TMP0]], [[START]]
-; CHECK-NEXT:    ret i1 false
+; CHECK-NEXT:    ret i1 [[TMP1]]
 ; CHECK:       exit:
 ; CHECK-NEXT:    ret i1 false
 ;
@@ -1255,7 +1255,7 @@
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    [[SHL_UB:%.*]] = shl nuw nsw i256 0, 64
 ; CHECK-NEXT:    [[SHL_CMP:%.*]] = icmp uge i256 [[SHL_UB]], 0
-; CHECK-NEXT:    ret i1 true
+; CHECK-NEXT:    ret i1 [[SHL_CMP]]
 ;
 entry:
   %shl.ub = shl nuw nsw i256 0, 64
@@ -1268,7 +1268,7 @@
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    [[SHL_UB:%.*]] = shl nuw nsw i256 0, 65
 ; CHECK-NEXT:    [[SHL_CMP:%.*]] = icmp uge i256 [[SHL_UB]], 0
-; CHECK-NEXT:    ret i1 true
+; CHECK-NEXT:    ret i1 [[SHL_CMP]]
 ;
 entry:
   %shl.ub = shl nuw nsw i256 0, 65