diff --git a/CMakeLists.txt b/CMakeLists.txt
index 23c3837d394..301f6176633 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -153,7 +153,7 @@ set(CMAKE_CXX_LINK_FLAGS "-Wl,--hash-style=gnu,-z,relro,-z,now")
 # This will need to be revisited when the Loader supports RPATH/RUN_PATH.
 set(CMAKE_SKIP_RPATH TRUE)
 
-add_compile_options(-O2 -g1 -fno-exceptions -fstack-protector-strong -Wno-address-of-packed-member -Wundef -Wcast-qual -Wwrite-strings -Wimplicit-fallthrough -Wno-nonnull-compare -Wno-deprecated-copy -Wno-expansion-to-defined)
+add_compile_options(-Os -g1 -fno-exceptions -fstack-protector-strong -Wno-address-of-packed-member -Wundef -Wcast-qual -Wwrite-strings -Wimplicit-fallthrough -Wno-nonnull-compare -Wno-deprecated-copy -Wno-expansion-to-defined)
 add_compile_options(-ffile-prefix-map=${CMAKE_SOURCE_DIR}=.)
 
 if ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")