--- old/src/hotspot/cpu/x86/macroAssembler_x86.cpp	2019-07-04 11:52:46.000000000 +0200
+++ new/src/hotspot/cpu/x86/macroAssembler_x86.cpp	2019-07-04 11:52:40.000000000 +0200
@@ -1754,6 +1754,10 @@
 
   // Attempt stack-locking ...
   orptr (tmpReg, markOopDesc::unlocked_value);
+  if (EnableValhalla && !UseBiasedLocking) {
+    // Mask always_locked bit such that we go to the slow path if object is a value type
+    andptr(tmpReg, ~markOopDesc::biased_lock_bit_in_place);
+  }
   movptr(Address(boxReg, 0), tmpReg);          // Anticipate successful CAS
   lock();
   cmpxchgptr(boxReg, Address(objReg, oopDesc::mark_offset_in_bytes()));      // Updates tmpReg