Index: lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
===================================================================
--- lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -1825,8 +1825,18 @@
       !match(Or1, m_OneUse(m_LogicalShift(m_Specific(ShVal), m_Value(ShAmt1)))))
     return nullptr;
 
-  auto ShiftOpcode0 = cast<BinaryOperator>(Or0)->getOpcode();
-  auto ShiftOpcode1 = cast<BinaryOperator>(Or1)->getOpcode();
+  auto getBinaryOperatorOrConstantExprOpcode = [](Value *V) -> unsigned {
+    if (auto TheBinaryOperator = dyn_cast<BinaryOperator>(V))
+      return unsigned(TheBinaryOperator->getOpcode());
+    else if (auto TheConstExpr = dyn_cast<ConstantExpr>(V))
+      return TheConstExpr->getOpcode();
+    else
+      llvm_unreachable(
+          "Expected Value to be either a BinaryOperator or ConstantExpr");
+  };
+
+  auto ShiftOpcode0 = getBinaryOperatorOrConstantExprOpcode(Or0);
+  auto ShiftOpcode1 = getBinaryOperatorOrConstantExprOpcode(Or1);
   if (ShiftOpcode0 == ShiftOpcode1)
     return nullptr;
 
Index: test/Transforms/InstCombine/rotate.ll
===================================================================
--- test/Transforms/InstCombine/rotate.ll
+++ test/Transforms/InstCombine/rotate.ll
@@ -689,3 +689,17 @@
   ret i24 %r
 }
 
+; Test that the transform doesn't crash when there's an "or" with a ConstantExpr operand.
+
+@external_global = external global i8
+
+define i32 @rotl_constant_expr(i32 %shamt) {
+; CHECK-LABEL: @rotl_constant_expr(
+; CHECK-NEXT:    [[SHR:%.*]] = lshr i32 ptrtoint (i8* @external_global to i32), [[SHAMT:%.*]]
+; CHECK-NEXT:    [[R:%.*]] = or i32 [[SHR]], shl (i32 ptrtoint (i8* @external_global to i32), i32 11)
+; CHECK-NEXT:    ret i32 [[R]]
+;
+  %shr = lshr i32 ptrtoint (i8* @external_global to i32), %shamt
+  %r = or i32 %shr, shl (i32 ptrtoint (i8* @external_global to i32), i32 11)
+  ret i32 %r
+}
\ No newline at end of file