--- old/src/java.base/share/classes/java/lang/invoke/MethodHandles.java	2018-01-30 23:31:13.780101738 -0500
+++ new/src/java.base/share/classes/java/lang/invoke/MethodHandles.java	2018-01-30 23:31:12.280016100 -0500
@@ -835,7 +835,7 @@
             }
             // Allow nestmate lookups to be created without special privilege:
             if ((newModes & PRIVATE) != 0
-                && !Reflection.areNestMates(this.lookupClass, requestedLookupClass)) {
+                && !VerifyAccess.areNestMates(this.lookupClass, requestedLookupClass)) {
                 newModes &= ~(PRIVATE|PROTECTED);
             }
             if ((newModes & PUBLIC) != 0
--- old/src/java.base/share/classes/sun/invoke/util/VerifyAccess.java	2018-01-30 23:31:18.208354539 -0500
+++ new/src/java.base/share/classes/sun/invoke/util/VerifyAccess.java	2018-01-30 23:31:16.724269815 -0500
@@ -133,7 +133,7 @@
         case PRIVATE:
             // Rules for privates follows access rules for nestmates.
             return ((allowedModes & PRIVATE) != 0 &&
-                    Reflection.areNestMates(defc, lookupClass));
+                    areNestMates(defc, lookupClass));
         default:
             throw new IllegalArgumentException("bad modifiers: "+Modifier.toString(mods));
         }
@@ -336,6 +336,33 @@
         return Objects.equals(class1.getPackageName(), class2.getPackageName());
     }
 
+    /**
+     * Test if two classes are defined as part of the same package member (top-level class).
+     * If this is true, they can share private access with each other.
+     * @param class1 a class
+     * @param class2 another class
+     * @return whether they are identical or nested together
+     */
+    public static boolean areNestMates(Class<?> class1, Class<?> class2) {
+        if (class1 == class2)
+            return true;
+        if (!isSamePackage(class1, class2))
+            return false;
+        if (Reflection.areNestMates(class1, class2))
+            return true;
+        // Could be pre-nestmate nested types
+        if (getOutermostEnclosingClass(class1) != getOutermostEnclosingClass(class2))
+            return false;
+        return true;
+    }
+
+    private static Class<?> getOutermostEnclosingClass(Class<?> c) {
+        Class<?> pkgmem = c;
+        for (Class<?> enc = c; (enc = enc.getEnclosingClass()) != null; )
+            pkgmem = enc;
+        return pkgmem;
+    }
+
     private static boolean loadersAreRelated(ClassLoader loader1, ClassLoader loader2,
                                              boolean loader1MustBeParent) {
         if (loader1 == loader2 || loader1 == null
--- /dev/null	2017-12-22 23:59:43.820328997 -0500
+++ new/test/hotspot/jtreg/runtime/Nestmates/legacy/TestPrivateLookup.java	2018-01-30 23:31:21.024515309 -0500
@@ -0,0 +1,106 @@
+/*
+ * Copyright (c) 2018, 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 8046171
+ * @summary Test that private Lookup works for both nestmate-enabled classes
+ * and legacy classes
+ * @run main TestPrivateLookup
+ * @compile -source 10 -target 10 TestPrivateLookup.java
+ * @run main TestPrivateLookup noNestmates
+ */
+import java.lang.invoke.*;
+import static java.lang.invoke.MethodHandles.*;
+import static java.lang.invoke.MethodType.*;
+
+public class TestPrivateLookup {
+
+    static boolean VMHasNestmates =
+        System.getProperty("java.vm.specification.version").equals("10");
+    static boolean compiledForNestmates;
+
+    static class C {
+        static class D {
+            private void m() { }
+        }
+
+        static void test() throws Throwable {
+            MethodType M_T = MethodType.methodType(void.class);
+            // Direct lookup from C
+            Lookup l = lookup();
+            try {
+                MethodHandle mh = l.findVirtual(D.class, "m", M_T);
+                if (compiledForNestmates) {
+                    System.out.println("Lookup of D.m from C succeeded as expected with nestmates");
+                }
+                else {
+                    throw new Error("Unexpected success when not compiled for nestmates!");
+                }
+            }
+            catch (IllegalAccessException iae) {
+                if (!compiledForNestmates) {
+                    System.out.println("Lookup of D.m from C failed as expected without nestmates");
+                }
+                else {
+                    throw new Error("Unexpected failure with nestmates", iae);
+                }
+            }
+            // switch lookup class to D
+            l = l.in(D.class);
+            try {
+                MethodHandle mh = l.findVirtual(D.class, "m", M_T);
+                System.out.println("Lookup of D.m from D succeeded as expected" +
+                                   " with" + (compiledForNestmates ? "" : "out") +
+                                   " nestmates");
+            }
+            catch (IllegalAccessException iae) {
+                throw new Error("Lookup of D.m from D failed", iae);
+            }
+        }
+    }
+
+    public static void main(String[] args) throws Throwable {
+        if (!VMHasNestmates) {
+            throw new Error("This test is only for JDK 11 with nestmates");
+        }
+
+        // If there's no nesthost attribute A.getNestHost() == A
+        compiledForNestmates = C.D.class.getNestHost() == TestPrivateLookup.class;
+        // sanity check
+        boolean expectingNestmates = args.length == 0;
+
+        if (compiledForNestmates && !expectingNestmates) {
+            throw new Error("Test is being run incorrectly: " +
+                            "nestmates are being used but not expected");
+        }
+        if (expectingNestmates && !compiledForNestmates) {
+            throw new Error("Test is being run incorrectly: ": +
+                            "nestmates are expected but not being used");
+        }
+        System.out.println("Testing with" + (expectingNestmates ? "" : "out") +
+                           " nestmates");
+
+        C.test();
+    }
+}