--- old/src/hotspot/cpu/x86/globals_x86.hpp	2018-12-03 14:35:23.803036717 +0100
+++ new/src/hotspot/cpu/x86/globals_x86.hpp	2018-12-03 14:35:23.463040077 +0100
@@ -104,8 +104,8 @@
 define_pd_global(bool, ThreadLocalHandshakes, false);
 #endif
 
-define_pd_global(bool, ValueTypePassFieldsAsArgs, LP64_ONLY(false) NOT_LP64(false));
-define_pd_global(bool, ValueTypeReturnedAsFields, LP64_ONLY(false) NOT_LP64(false));
+define_pd_global(bool, ValueTypePassFieldsAsArgs, LP64_ONLY(true) NOT_LP64(false));
+define_pd_global(bool, ValueTypeReturnedAsFields, LP64_ONLY(true) NOT_LP64(false));
 
 #define ARCH_FLAGS(develop, \
                    product, \