--- a/make/autoconf/flags-cflags.m4
+++ b/make/autoconf/flags-cflags.m4
@@ -264,13 +264,13 @@
       C_O_FLAG_NORM="-Os"
       C_O_FLAG_DEBUG_JVM=""
     else
-      C_O_FLAG_HIGHEST_JVM="-O3"
-      C_O_FLAG_HIGHEST="-O3"
-      C_O_FLAG_HI="-O3"
-      C_O_FLAG_NORM="-O2"
+      C_O_FLAG_HIGHEST_JVM=""
+      C_O_FLAG_HIGHEST=""
+      C_O_FLAG_HI=""
+      C_O_FLAG_NORM="" # FIXME
       C_O_FLAG_DEBUG_JVM="-O0"
     fi
-    C_O_FLAG_SIZE="-Os"
+    C_O_FLAG_SIZE=""
     C_O_FLAG_DEBUG="-O0"
     C_O_FLAG_NONE="-O0"
   elif test "x$TOOLCHAIN_TYPE" = xxlc; then