--- old/src/hotspot/share/runtime/arguments.cpp	2017-10-30 15:12:30.518371350 +0100
+++ new/src/hotspot/share/runtime/arguments.cpp	2017-10-30 15:12:30.174360045 +0100
@@ -4616,16 +4616,35 @@
 
   bool aot_enabled = UseAOT && ((AOTLibrary != NULL) || !FLAG_IS_DEFAULT(UseAOT));
   bool jvmci_enabled = NOT_JVMCI(false) JVMCI_ONLY(EnableJVMCI || UseJVMCICompiler);
-  bool handshakes_supported = SafepointMechanism::supports_thread_local_poll() && !aot_enabled && !jvmci_enabled;
+  bool handshakes_supported = SafepointMechanism::supports_thread_local_poll() && !aot_enabled && !jvmci_enabled && ThreadLocalHandshakes;
+  // ThreadLocalHandshakesConstraintFunc handles the constraints.
+  // Here we try to figure out if a mutual exclusive option have been set.
   if (handshakes_supported) {
     if (FLAG_IS_DEFAULT(UseAOT)) {
       FLAG_SET_DEFAULT(UseAOT, false); // Clear the AOT flag to make sure it doesn't try to initialize.
     }
-    if (FLAG_IS_DEFAULT(ThreadLocalHandshakes) && !ThreadLocalHandshakes) {
-      FLAG_SET_ERGO(bool, ThreadLocalHandshakes, true);
-      log_info(ergo)("Enabling ThreadLocalHandshakes on supported platform");
+  } else {
+    if (FLAG_IS_DEFAULT(ThreadLocalHandshakes) && ThreadLocalHandshakes) {
+      if (!SafepointMechanism::supports_thread_local_poll()) {
+        // Unsupported platform should have ThreadLocalHandshakes default set to false.
+        log_debug(ergo)("Disabling ThreadLocalHandshakes unsupported plaform.");
+        FLAG_SET_ERGO(bool, ThreadLocalHandshakes, false);
+      } else if (!FLAG_IS_DEFAULT(UseAOT) && UseAOT) {
+        // If user enabled AOT but ThreadLocalHandshakes is at default set it to false.
+        log_debug(ergo)("Disabling ThreadLocalHandshakes for UseAOT.");
+        FLAG_SET_ERGO(bool, ThreadLocalHandshakes, false);
+      } else if (jvmci_enabled){
+        // If user enabled JVMCI but ThreadLocalHandshakes is at default set it to false.
+        log_debug(ergo)("Disabling ThreadLocalHandshakes for EnableJVMCI/UseJVMCICompiler.");
+        FLAG_SET_ERGO(bool, ThreadLocalHandshakes, false);
+      }
     }
   }
+  if (FLAG_IS_DEFAULT(ThreadLocalHandshakes) || !SafepointMechanism::supports_thread_local_poll()) {
+    log_debug(ergo)("ThreadLocalHandshakes %s", ThreadLocalHandshakes ? "enabled." : "disabled.");
+  } else {
+    log_info(ergo)("ThreadLocalHandshakes %s", ThreadLocalHandshakes ? "enabled." : "disabled.");
+  }
 
   return JNI_OK;
 }
--- old/src/hotspot/share/runtime/globals.hpp	2017-10-30 15:12:31.503403722 +0100
+++ new/src/hotspot/share/runtime/globals.hpp	2017-10-30 15:12:31.248395341 +0100
@@ -598,7 +598,7 @@
   develop(bool, CleanChunkPoolAsync, true,                                  \
           "Clean the chunk pool asynchronously")                            \
                                                                             \
-  product(bool, ThreadLocalHandshakes, false,                               \
+  product(bool, ThreadLocalHandshakes, true,                                \
           "Use thread-local polls instead of global poll for safepoints.")  \
           constraint(ThreadLocalHandshakesConstraintFunc,AfterErgo)         \
                                                                             \