diff --git a/Kconfig.zephyr b/Kconfig.zephyr
index 5e6694b1c21..3cab0519b45 100644
--- a/Kconfig.zephyr
+++ b/Kconfig.zephyr
@@ -478,6 +478,7 @@ choice COMPILER_OPTIMIZATIONS
 	prompt "Optimization level"
 	default NO_OPTIMIZATIONS    if COVERAGE
 	default DEBUG_OPTIMIZATIONS if DEBUG
+	default SIZE_OPTIMIZATIONS_AGGRESSIVE if "$(ZEPHYR_TOOLCHAIN_VARIANT)" = "llvm"
 	default SIZE_OPTIMIZATIONS
 	help
 	  Note that these flags shall only control the compiler