diff --git a/compiler-rt/lib/builtins/CMakeLists.txt b/compiler-rt/lib/builtins/CMakeLists.txt
--- a/compiler-rt/lib/builtins/CMakeLists.txt
+++ b/compiler-rt/lib/builtins/CMakeLists.txt
@@ -531,8 +531,7 @@
     foreach(model 1 2 3 4)
       if(pat STREQUAL "cas" OR NOT size STREQUAL "16")
         set(helper_asm "${OA_HELPERS_DIR}/outline_atomic_${pat}${size}_${model}.S")
-        add_custom_command(
-          OUTPUT ${helper_asm}
+        execute_process(
           COMMAND ${CMAKE_COMMAND} -E ${COMPILER_RT_LINK_OR_COPY} "${CMAKE_CURRENT_SOURCE_DIR}/aarch64/lse.S" "${helper_asm}"
         )
         set_source_files_properties("${helper_asm}"