diff --git a/flang/lib/Optimizer/HLFIR/Transforms/SimplifyHLFIRIntrinsics.cpp b/flang/lib/Optimizer/HLFIR/Transforms/SimplifyHLFIRIntrinsics.cpp
index 3e9d956b6e56d..a90c5a9ef5a4e 100644
--- a/flang/lib/Optimizer/HLFIR/Transforms/SimplifyHLFIRIntrinsics.cpp
+++ b/flang/lib/Optimizer/HLFIR/Transforms/SimplifyHLFIRIntrinsics.cpp
@@ -33,7 +33,8 @@ namespace hlfir {
 static llvm::cl::opt<bool>
     simplifySum("flang-simplify-hlfir-sum",
                 llvm::cl::desc("Expand hlfir.sum into an inline sequence"),
-                llvm::cl::init(false));
+                llvm::cl::init(true));
+
 namespace {
 
 class TransposeAsElementalConversion