--- a/hotspot/src/share/vm/runtime/arguments.cpp	Thu Jun 25 13:23:36 2015 +0000
+++ b/hotspot/src/share/vm/runtime/arguments.cpp	Thu Jun 25 18:25:19 2015 +0200
@@ -1582,6 +1582,9 @@
   // in vm_version initialization code.
 #endif // _LP64
 #endif // !ZERO
+
+  // Set up runtime image flags.
+  set_runtime_image_flags();
 }
 
 void Arguments::set_parallel_gc_flags() {
@@ -1837,6 +1840,16 @@
   }
 }
 
+  // Set up runtime image flags
+void Arguments::set_runtime_image_flags() {
+#ifdef _LP64
+  // Memory map image file by default on 64 bit machines.
+  if (FLAG_IS_DEFAULT(MemoryMapImage)) {
+    FLAG_SET_ERGO(bool, MemoryMapImage, true);
+  }
+#endif
+}
+
 // This must be called after ergonomics.
 void Arguments::set_bytecode_flags() {
   if (!RewriteBytecodes) {