diff a/test/micro/org/openjdk/bench/valhalla/corelibs/mapprotos/HashMapBench.java b/test/micro/org/openjdk/bench/valhalla/corelibs/mapprotos/HashMapBench.java
--- /dev/null
+++ b/test/micro/org/openjdk/bench/valhalla/corelibs/mapprotos/HashMapBench.java
@@ -0,0 +1,117 @@
+/*
+ * Copyright (c) 2018, Red Hat, Inc. All rights reserved.
+ *
+ * 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.
+ */
+
+package org.openjdk.bench.valhalla.corelibs.mapprotos;
+
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Fork;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+import org.openjdk.jmh.annotations.Param;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.Setup;
+import org.openjdk.jmh.annotations.State;
+
+import java.util.HashMap;
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.concurrent.ThreadLocalRandom;
+import java.util.concurrent.TimeUnit;
+import java.util.function.IntFunction;
+import java.util.stream.IntStream;
+
+import static java.util.stream.Collectors.toMap;
+
+/**
+ * Benchmark                                    (mapType)   (size)  Mode  Cnt    Score    Error  Units
+ * XHashMapBench.put                             HASH_MAP  1000000  avgt    5  214.470 +/- 44.063  ms/op
+ * XHashMapBench.put                            XHASH_MAP  1000000  avgt    5  215.772 +/- 31.595  ms/op
+ * XHashMapBench.putAllWithBigMapToEmptyMap      HASH_MAP  1000000  avgt    5  126.472 +/- 38.452  ms/op
+ * XHashMapBench.putAllWithBigMapToEmptyMap     XHASH_MAP  1000000  avgt    5  117.741 +/- 10.460  ms/op
+ * XHashMapBench.putAllWithBigMapToNonEmptyMap   HASH_MAP  1000000  avgt    5  136.112 +/- 36.712  ms/op
+ * XHashMapBench.putAllWithBigMapToNonEmptyMap  XHASH_MAP  1000000  avgt    5  144.681 +/-  8.755  ms/op
+ * Finished running test 'micro:valhalla.corelibs.XHashMapBench'
+ */
+@BenchmarkMode(Mode.AverageTime)
+@OutputTimeUnit(TimeUnit.MILLISECONDS)
+@Fork(1)
+@State(Scope.Thread)
+public class HashMapBench {
+    private IntFunction<Map<Integer, Integer>> mapSupplier;
+    private Map<Integer, Integer> bigMapToAdd;
+
+    @Param("1000000")
+    private int size;
+
+    @Param(value = {"org.openjdk.bench.valhalla.corelibs.mapprotos.YHashMap",
+            "org.openjdk.bench.valhalla.corelibs.mapprotos.XHashMap",
+            "java.util.HashMap"})
+    private String mapType;
+
+    @Setup
+    public void setup() {
+        try {
+            Class<?> mapClass = Class.forName(mapType);
+            mapSupplier =  (size) -> newInstance(mapClass, size);
+        } catch (Exception ex) {
+            System.out.printf("%s: %s%n", mapType, ex.getMessage());
+            return;
+        }
+
+        ThreadLocalRandom rnd = ThreadLocalRandom.current();
+        this.bigMapToAdd = IntStream.range(0, size).boxed()
+            .collect(toMap(i -> 7 + i * 128, i -> rnd.nextInt()));
+    }
+
+    Map<Integer, Integer> newInstance(Class<?> mapClass, int size) {
+        try {
+            return (Map<Integer, Integer>)mapClass.getConstructor(int.class).newInstance(size);
+        } catch (Exception ex) {
+            throw new RuntimeException("failed", ex);
+        }
+    }
+
+    @Benchmark
+    public int putAllWithBigMapToNonEmptyMap() {
+        Map<Integer, Integer> map = mapSupplier.apply(16);
+        map.put(-1, -1);
+        map.putAll(bigMapToAdd);
+        return map.size();
+    }
+
+    @Benchmark
+    public int putAllWithBigMapToEmptyMap() {
+        Map<Integer, Integer> map = mapSupplier.apply(16);
+        map.putAll(bigMapToAdd);
+        return map.size();
+    }
+
+    @Benchmark
+    public int put() {
+        Map<Integer, Integer> map = mapSupplier.apply(16);
+        for (int k : bigMapToAdd.keySet()) {
+            map.put(k, bigMapToAdd.get(k));
+        }
+        return map.size();
+    }
+}