--- a/hotspot/src/share/vm/prims/unsafe.cpp	Thu Mar 24 10:40:23 2016 +0100
+++ b/hotspot/src/share/vm/prims/unsafe.cpp	Thu Mar 24 08:13:28 2016 -0400
@@ -905,7 +905,10 @@
   }
 
   const Klass* host_klass = java_lang_Class::as_Klass(JNIHandles::resolve_non_null(host_class));
-  assert(host_klass != NULL, "invariant");
+  // Primitive types have NULL Klass* fields in their java.lang.Class instances.
+  if (host_klass == NULL) {
+    THROW_0(vmSymbols::java_lang_IllegalArgumentException());
+  }
 
   const char* host_source = host_klass->external_name();
   Handle      host_loader(THREAD, host_klass->class_loader());

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/test/runtime/Unsafe/PrimitiveHostClass.java	Thu Mar 24 08:13:28 2016 -0400
@@ -0,0 +1,99 @@
+/*
+ * Copyright (c) 2016, 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.
+ */
+
+import java.awt.Component;
+import java.lang.reflect.Field;
+import static jdk.internal.org.objectweb.asm.Opcodes.*;
+import jdk.internal.org.objectweb.asm.*;
+import sun.misc.Unsafe;
+
+/*
+ * @test PrimitiveHostClass
+ * @bug 8140665
+ * @summary Throws IllegalArgumentException if host class is a primitive class.
+ * @library /testlibrary
+ * @modules java.base/jdk.internal.org.objectweb.asm
+ *          java.base/sun.misc
+ * @compile -XDignore.symbol.file PrimitiveHostClass.java
+ * @run main/othervm PrimitiveHostClass
+ */
+
+public class PrimitiveHostClass {
+
+    static final Unsafe U;
+    static {
+        try {
+            Field theUnsafe = Unsafe.class.getDeclaredField("theUnsafe");
+            theUnsafe.setAccessible(true);
+            U = (Unsafe) theUnsafe.get(null);
+        } catch (Exception e) {
+            throw new AssertionError(e);
+        }
+    }
+
+    public static void testVMAnonymousClass(Class<?> hostClass) {
+
+        // choose a class name in the same package as the host class
+        String prefix = packageName(hostClass);
+        if (prefix.length() > 0)
+            prefix = prefix.replace('.', '/') + "/";
+        String className = prefix + "Anon";
+
+        // create the class
+        String superName = "java/lang/Object";
+        ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_MAXS
+                                         + ClassWriter.COMPUTE_FRAMES);
+        cw.visit(V1_8, ACC_PUBLIC + ACC_FINAL + ACC_SUPER,
+                 className, null, superName, null);
+        byte[] classBytes = cw.toByteArray();
+        int cpPoolSize = constantPoolSize(classBytes);
+        Class<?> anonClass =
+            U.defineAnonymousClass(hostClass, classBytes, new Object[cpPoolSize]);
+    }
+
+    private static String packageName(Class<?> c) {
+        if (c.isArray()) {
+            return packageName(c.getComponentType());
+        } else {
+            String name = c.getName();
+            int dot = name.lastIndexOf('.');
+            if (dot == -1) return "";
+            return name.substring(0, dot);
+        }
+    }
+
+    private static int constantPoolSize(byte[] classFile) {
+        return ((classFile[8] & 0xFF) << 8) | (classFile[9] & 0xFF);
+    }
+
+    public static void main(String args[]) {
+        testVMAnonymousClass(PrimitiveHostClass.class);
+        try {
+            testVMAnonymousClass(int.class);
+            throw new RuntimeException(
+                "Expected IllegalArgumentException not thrown");
+        } catch (IllegalArgumentException e) {
+            // Expected
+        }
+    }
+}