--- a/hotspot/src/share/vm/oops/klassVtable.cpp	Mon Jan 05 12:07:37 2015 -0500
+++ b/hotspot/src/share/vm/oops/klassVtable.cpp	Mon Jan 05 22:50:59 2015 -0500
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2015, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -100,17 +100,21 @@
     vtable_length = Universe::base_vtable_size();
   }
 
-  if (super == NULL && !Universe::is_bootstrapping() &&
-      vtable_length != Universe::base_vtable_size()) {
-    // Someone is attempting to redefine java.lang.Object incorrectly.  The
-    // only way this should happen is from
-    // SystemDictionary::resolve_from_stream(), which will detect this later
-    // and throw a security exception.  So don't assert here to let
-    // the exception occur.
-    vtable_length = Universe::base_vtable_size();
+  if (super == NULL && vtable_length != Universe::base_vtable_size()) {
+    if (Universe::is_bootstrapping()) {
+      // Someone is attempting to override java.lang.Object incorrectly on the
+      // bootclasspath.  The JVM cannot recover from this error including throwing
+      // an exception
+      vm_exit_during_initialization("Incompatible definition of java.lang.Object");
+    } else {
+      // Someone is attempting to redefine java.lang.Object incorrectly.  The
+      // only way this should happen is from
+      // SystemDictionary::resolve_from_stream(), which will detect this later
+      // and throw a security exception.  So don't assert here to let
+      // the exception occur.
+      vtable_length = Universe::base_vtable_size();
+    }
   }
-  assert(super != NULL || vtable_length == Universe::base_vtable_size(),
-         "bad vtable size for class Object");
   assert(vtable_length % vtableEntry::size() == 0, "bad vtable length");
   assert(vtable_length >= Universe::base_vtable_size(), "vtable too small");
 

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/test/runtime/BadObjectClass/BootstrapRedefine.java	Mon Jan 05 22:50:59 2015 -0500
@@ -0,0 +1,44 @@
+/*
+ * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug 6583051
+ * @summary Give error if java.lang.Object has been incompatibly overridden on the bootpath
+ * @library /testlibrary
+ * @compile Object.java
+ * @run main BootstrapRedefine
+ */
+
+import com.oracle.java.testlibrary.*;
+
+public class BootstrapRedefine {
+
+    public static void main(String[] args) throws Exception {
+        String testClasses = System.getProperty("test.classes", ".");
+        ProcessBuilder pb = ProcessTools.createJavaProcessBuilder("-Xbootclasspath/p:" + testClasses, "-version");
+        new OutputAnalyzer(pb.start())
+            .shouldContain("Incompatible definition of java.lang.Object")
+            .shouldHaveExitValue(1);
+    }
+}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/test/runtime/BadObjectClass/Object.java	Mon Jan 05 22:50:59 2015 -0500
@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package java.lang;
+
+/**
+ * This is a fake java.lang.Object class.
+ */
+public class Object {
+
+    // Add some methods
+    void dummy1() { return; }
+    void dummy2() { return; }
+    void dummy3() { return; }
+}