--- old/make/linux/makefiles/vm.make	2018-09-04 17:07:11.524138539 +0200
+++ new/make/linux/makefiles/vm.make	2018-09-04 17:07:11.369138841 +0200
@@ -121,7 +121,13 @@
 CFLAGS += $(CFLAGS/NOEX)
 
 # Extra flags from gnumake's invocation or environment
-CFLAGS += $(EXTRA_CFLAGS)
+#
+# Disallow lowering of hotspot optimization via
+# EXTRA_CFLAGS. This is controlled via
+# OPT_EXTRAS make variable if so desired. See
+# JDK-8210352 for more info.
+CFLAGS += $(subst -O0,, $(subst -O2,, \
+            $(subst -O1,, $(EXTRA_CFLAGS))))
 LFLAGS += $(EXTRA_CFLAGS) $(EXTRA_LDFLAGS)
 
 # Don't set excutable bit on stack segment