diff --git a/cmake/adjust_global_compile_flags.cmake b/cmake/adjust_global_compile_flags.cmake
index 442654ff44..6859991134 100644
--- a/cmake/adjust_global_compile_flags.cmake
+++ b/cmake/adjust_global_compile_flags.cmake
@@ -29,8 +29,8 @@ if (CMAKE_SYSTEM_NAME STREQUAL "Emscripten")
     # (2) "-flto=thin" does not work correctly for wasm-ld.
     #     we don't set onnxruntime_ENABLE_LTO because it appends flag "-flto=thin"
     #     instead, we manually set CMAKE_CXX_FLAGS "-flto"
-    #string(APPEND CMAKE_C_FLAGS " -flto")
-    #string(APPEND CMAKE_CXX_FLAGS " -flto")
+    string(APPEND CMAKE_C_FLAGS " -flto")
+    string(APPEND CMAKE_CXX_FLAGS " -flto")
   endif()
 
   if (onnxruntime_ENABLE_WEBASSEMBLY_DEBUG_INFO)