diff --git a/src/Common/src/CoreLib/System.Private.CoreLib.Shared.projitems b/src/Common/src/CoreLib/System.Private.CoreLib.Shared.projitems
index 4ab59240948f..8cfd499edb16 100644
--- a/src/Common/src/CoreLib/System.Private.CoreLib.Shared.projitems
+++ b/src/Common/src/CoreLib/System.Private.CoreLib.Shared.projitems
@@ -159,6 +159,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\UmAlQuraCalendar.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Globalization\UnicodeCategory.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\Guid.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)System\HashCode.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\HResults.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\IAsyncResult.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)System\ICloneable.cs" />
diff --git a/src/Common/src/CoreLib/System/HashCode.cs b/src/Common/src/CoreLib/System/HashCode.cs
new file mode 100644
index 000000000000..4be57be02a9a
--- /dev/null
+++ b/src/Common/src/CoreLib/System/HashCode.cs
@@ -0,0 +1,430 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+/*
+
+The xxHash32 implementation is based on the code published by Yann Collet:
+https://raw.githubusercontent.com/Cyan4973/xxHash/5c174cfa4e45a42f94082dc0d4539b39696afea1/xxhash.c
+
+  xxHash - Fast Hash algorithm
+  Copyright (C) 2012-2016, Yann Collet
+  
+  BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
+  
+  Redistribution and use in source and binary forms, with or without
+  modification, are permitted provided that the following conditions are
+  met:
+  
+  * Redistributions of source code must retain the above copyright
+  notice, this list of conditions and the following disclaimer.
+  * Redistributions in binary form must reproduce the above
+  copyright notice, this list of conditions and the following disclaimer
+  in the documentation and/or other materials provided with the
+  distribution.
+  
+  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+  A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+  OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+  
+  You can contact the author at :
+  - xxHash homepage: http://www.xxhash.com
+  - xxHash source repository : https://github.com/Cyan4973/xxHash
+
+*/
+
+using System.Collections.Generic;
+using System.ComponentModel;
+using System.Runtime.CompilerServices;
+
+namespace System
+{
+    // xxHash32 is used for the hash code.
+    // https://github.com/Cyan4973/xxHash
+
+    public struct HashCode
+    {
+        private static readonly uint s_seed = GenerateGlobalSeed();
+
+        private const uint Prime1 = 2654435761U;
+        private const uint Prime2 = 2246822519U;
+        private const uint Prime3 = 3266489917U;
+        private const uint Prime4 = 668265263U;
+        private const uint Prime5 = 374761393U;
+
+        private uint _v1, _v2, _v3, _v4;
+        private uint _queue1, _queue2, _queue3;
+        private uint _length;
+
+        private static unsafe uint GenerateGlobalSeed()
+        {
+            uint result;
+            Interop.GetRandomBytes((byte*)&result, sizeof(uint));
+            return result;
+        }
+
+        public static int Combine<T1>(T1 value1)
+        {
+            // Provide a way of diffusing bits from something with a limited
+            // input hash space. For example, many enums only have a few
+            // possible hashes, only using the bottom few bits of the code. Some
+            // collections are built on the assumption that hashes are spread
+            // over a larger space, so diffusing the bits may help the
+            // collection work more efficiently.
+
+            var hc1 = (uint)(value1?.GetHashCode() ?? 0);
+
+            uint hash = MixEmptyState();
+            hash += 4;
+
+            hash = QueueRound(hash, hc1);
+
+            hash = MixFinal(hash);
+            return (int)hash;
+        }
+
+        public static int Combine<T1, T2>(T1 value1, T2 value2)
+        {
+            var hc1 = (uint)(value1?.GetHashCode() ?? 0);
+            var hc2 = (uint)(value2?.GetHashCode() ?? 0);
+
+            uint hash = MixEmptyState();
+            hash += 8;
+
+            hash = QueueRound(hash, hc1);
+            hash = QueueRound(hash, hc2);
+
+            hash = MixFinal(hash);
+            return (int)hash;
+        }
+
+        public static int Combine<T1, T2, T3>(T1 value1, T2 value2, T3 value3)
+        {
+            var hc1 = (uint)(value1?.GetHashCode() ?? 0);
+            var hc2 = (uint)(value2?.GetHashCode() ?? 0);
+            var hc3 = (uint)(value3?.GetHashCode() ?? 0);
+
+            uint hash = MixEmptyState();
+            hash += 12;
+
+            hash = QueueRound(hash, hc1);
+            hash = QueueRound(hash, hc2);
+            hash = QueueRound(hash, hc3);
+
+            hash = MixFinal(hash);
+            return (int)hash;
+        }
+
+        public static int Combine<T1, T2, T3, T4>(T1 value1, T2 value2, T3 value3, T4 value4)
+        {
+            var hc1 = (uint)(value1?.GetHashCode() ?? 0);
+            var hc2 = (uint)(value2?.GetHashCode() ?? 0);
+            var hc3 = (uint)(value3?.GetHashCode() ?? 0);
+            var hc4 = (uint)(value4?.GetHashCode() ?? 0);
+
+            Initialize(out uint v1, out uint v2, out uint v3, out uint v4);
+
+            v1 = Round(v1, hc1);
+            v2 = Round(v2, hc2);
+            v3 = Round(v3, hc3);
+            v4 = Round(v4, hc4);
+
+            uint hash = MixState(v1, v2, v3, v4);
+            hash += 16;
+
+            hash = MixFinal(hash);
+            return (int)hash;
+        }
+
+        public static int Combine<T1, T2, T3, T4, T5>(T1 value1, T2 value2, T3 value3, T4 value4, T5 value5)
+        {
+            var hc1 = (uint)(value1?.GetHashCode() ?? 0);
+            var hc2 = (uint)(value2?.GetHashCode() ?? 0);
+            var hc3 = (uint)(value3?.GetHashCode() ?? 0);
+            var hc4 = (uint)(value4?.GetHashCode() ?? 0);
+            var hc5 = (uint)(value5?.GetHashCode() ?? 0);
+
+            Initialize(out uint v1, out uint v2, out uint v3, out uint v4);
+
+            v1 = Round(v1, hc1);
+            v2 = Round(v2, hc2);
+            v3 = Round(v3, hc3);
+            v4 = Round(v4, hc4);
+
+            uint hash = MixState(v1, v2, v3, v4);
+            hash += 20;
+
+            hash = QueueRound(hash, hc5);
+
+            hash = MixFinal(hash);
+            return (int)hash;
+        }
+
+        public static int Combine<T1, T2, T3, T4, T5, T6>(T1 value1, T2 value2, T3 value3, T4 value4, T5 value5, T6 value6)
+        {
+            var hc1 = (uint)(value1?.GetHashCode() ?? 0);
+            var hc2 = (uint)(value2?.GetHashCode() ?? 0);
+            var hc3 = (uint)(value3?.GetHashCode() ?? 0);
+            var hc4 = (uint)(value4?.GetHashCode() ?? 0);
+            var hc5 = (uint)(value5?.GetHashCode() ?? 0);
+            var hc6 = (uint)(value6?.GetHashCode() ?? 0);
+
+            Initialize(out uint v1, out uint v2, out uint v3, out uint v4);
+
+            v1 = Round(v1, hc1);
+            v2 = Round(v2, hc2);
+            v3 = Round(v3, hc3);
+            v4 = Round(v4, hc4);
+
+            uint hash = MixState(v1, v2, v3, v4);
+            hash += 24;
+
+            hash = QueueRound(hash, hc5);
+            hash = QueueRound(hash, hc6);
+
+            hash = MixFinal(hash);
+            return (int)hash;
+        }
+
+        public static int Combine<T1, T2, T3, T4, T5, T6, T7>(T1 value1, T2 value2, T3 value3, T4 value4, T5 value5, T6 value6, T7 value7)
+        {
+            var hc1 = (uint)(value1?.GetHashCode() ?? 0);
+            var hc2 = (uint)(value2?.GetHashCode() ?? 0);
+            var hc3 = (uint)(value3?.GetHashCode() ?? 0);
+            var hc4 = (uint)(value4?.GetHashCode() ?? 0);
+            var hc5 = (uint)(value5?.GetHashCode() ?? 0);
+            var hc6 = (uint)(value6?.GetHashCode() ?? 0);
+            var hc7 = (uint)(value7?.GetHashCode() ?? 0);
+
+            Initialize(out uint v1, out uint v2, out uint v3, out uint v4);
+
+            v1 = Round(v1, hc1);
+            v2 = Round(v2, hc2);
+            v3 = Round(v3, hc3);
+            v4 = Round(v4, hc4);
+
+            uint hash = MixState(v1, v2, v3, v4);
+            hash += 28;
+
+            hash = QueueRound(hash, hc5);
+            hash = QueueRound(hash, hc6);
+            hash = QueueRound(hash, hc7);
+
+            hash = MixFinal(hash);
+            return (int)hash;
+        }
+
+        public static int Combine<T1, T2, T3, T4, T5, T6, T7, T8>(T1 value1, T2 value2, T3 value3, T4 value4, T5 value5, T6 value6, T7 value7, T8 value8)
+        {
+            var hc1 = (uint)(value1?.GetHashCode() ?? 0);
+            var hc2 = (uint)(value2?.GetHashCode() ?? 0);
+            var hc3 = (uint)(value3?.GetHashCode() ?? 0);
+            var hc4 = (uint)(value4?.GetHashCode() ?? 0);
+            var hc5 = (uint)(value5?.GetHashCode() ?? 0);
+            var hc6 = (uint)(value6?.GetHashCode() ?? 0);
+            var hc7 = (uint)(value7?.GetHashCode() ?? 0);
+            var hc8 = (uint)(value8?.GetHashCode() ?? 0);
+
+            Initialize(out uint v1, out uint v2, out uint v3, out uint v4);
+
+            v1 = Round(v1, hc1);
+            v2 = Round(v2, hc2);
+            v3 = Round(v3, hc3);
+            v4 = Round(v4, hc4);
+
+            v1 = Round(v1, hc5);
+            v2 = Round(v2, hc6);
+            v3 = Round(v3, hc7);
+            v4 = Round(v4, hc8);
+
+            uint hash = MixState(v1, v2, v3, v4);
+            hash += 32;
+
+            hash = MixFinal(hash);
+            return (int)hash;
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static uint Rol(uint value, int count)
+            => (value << count) | (value >> (32 - count));
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static void Initialize(out uint v1, out uint v2, out uint v3, out uint v4)
+        {
+            v1 = s_seed + Prime1 + Prime2;
+            v2 = s_seed + Prime2;
+            v3 = s_seed;
+            v4 = s_seed - Prime1;
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static uint Round(uint hash, uint input)
+        {
+            hash += input * Prime2;
+            hash = Rol(hash, 13);
+            hash *= Prime1;
+            return hash;
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static uint QueueRound(uint hash, uint queuedValue)
+        {
+            hash += queuedValue * Prime3;
+            return Rol(hash, 17) * Prime4;
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static uint MixState(uint v1, uint v2, uint v3, uint v4)
+        {
+            return Rol(v1, 1) + Rol(v2, 7) + Rol(v3, 12) + Rol(v4, 18);
+        }
+
+        private static uint MixEmptyState()
+        {
+            return s_seed + Prime5;
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static uint MixFinal(uint hash)
+        {
+            hash ^= hash >> 15;
+            hash *= Prime2;
+            hash ^= hash >> 13;
+            hash *= Prime3;
+            hash ^= hash >> 16;
+            return hash;
+        }
+
+        public void Add<T>(T value)
+        {
+            Add(value?.GetHashCode() ?? 0);
+        }
+
+        public void Add<T>(T value, IEqualityComparer<T> comparer)
+        {
+            Add(comparer != null ? comparer.GetHashCode(value) : (value?.GetHashCode() ?? 0));
+        }
+
+        private void Add(int value)
+        {
+            // The original xxHash works as follows:
+            // 0. Initialize immediately. We can't do this in a struct (no
+            //    default ctor).
+            // 1. Accumulate blocks of length 16 (4 uints) into 4 accumulators.
+            // 2. Accumulate remaining blocks of length 4 (1 uint) into the
+            //    hash.
+            // 3. Accumulate remaining blocks of length 1 into the hash.
+
+            // There is no need for #3 as this type only accepts ints. _queue1,
+            // _queue2 and _queue3 are basically a buffer so that when
+            // ToHashCode is called we can execute #2 correctly.
+
+            // We need to initialize the xxHash32 state (_v1 to _v4) lazily (see
+            // #0) nd the last place that can be done if you look at the
+            // original code is just before the first block of 16 bytes is mixed
+            // in. The xxHash32 state is never used for streams containing fewer
+            // than 16 bytes.
+
+            // To see what's really going on here, have a look at the Combine
+            // methods.
+            
+            var val = (uint)value;
+            
+            // Storing the value of _length locally shaves of quite a few bytes
+            // in the resulting machine code.
+            uint previousLength = _length++;
+            uint position = previousLength % 4;
+
+            // Switch can't be inlined.
+
+            if (position == 0)
+                _queue1 = val;
+            else if (position == 1)
+                _queue2 = val;
+            else if (position == 2)
+                _queue3 = val;
+            else // position == 3
+            {
+                if (previousLength == 3)
+                    Initialize(out _v1, out _v2, out _v3, out _v4);
+
+                _v1 = Round(_v1, _queue1);
+                _v2 = Round(_v2, _queue2);
+                _v3 = Round(_v3, _queue3);
+                _v4 = Round(_v4, val);
+            }
+        }
+
+        public int ToHashCode()
+        {
+            // Storing the value of _length locally shaves of quite a few bytes
+            // in the resulting machine code.
+            uint length = _length;
+            
+            // position refers to the *next* queue position in this method, so
+            // position == 1 means that _queue1 is populated; _queue2 would have
+            // been populated on the next call to Add.
+            uint position = length % 4;
+
+            // If the length is less than 4, _v1 to _v4 don't contain anything
+            // yet. xxHash32 treats this differently.
+
+            uint hash = length < 4 ? MixEmptyState() : MixState(_v1, _v2, _v3, _v4);
+
+            // _length is incremented once per Add(Int32) and is therefore 4
+            // times too small (xxHash length is in bytes, not ints).
+
+            hash += length * 4;
+
+            // Mix what remains in the queue
+
+            // Switch can't be inlined right now, so use as few branches as
+            // possible by manually excluding impossible scenarios (position > 1
+            // is always false if position is not > 0).
+            if (position > 0)
+            {
+                hash = QueueRound(hash, _queue1);
+                if (position > 1)
+                {
+                    hash = QueueRound(hash, _queue2);
+                    if (position > 2)
+                        hash = QueueRound(hash, _queue3);
+                }
+            }
+
+            hash = MixFinal(hash);
+            return (int)hash;
+        }
+
+#pragma warning disable 0809
+        // Obsolete member 'memberA' overrides non-obsolete member 'memberB'. 
+        // Disallowing GetHashCode and Equals is by design
+
+        // * We decided to not override GetHashCode() to produce the hash code 
+        //   as this would be weird, both naming-wise as well as from a
+        //   behavioral standpoint (GetHashCode() should return the object's
+        //   hash code, not the one being computed).
+
+        // * Even though ToHashCode() can be called safely multiple times on
+        //   this implementation, it is not part of the contract. If the
+        //   implementation has to change in the future we don't want to worry
+        //   about people who might have incorrectly used this type.
+
+        [Obsolete("HashCode is a mutable struct and should not be compared with other HashCodes. Use ToHashCode to retrieve the computed hash code.", error: true)]
+        [EditorBrowsable(EditorBrowsableState.Never)]
+        public override int GetHashCode() => throw new NotSupportedException(SR.HashCode_HashCodeNotSupported);
+
+        [Obsolete("HashCode is a mutable struct and should not be compared with other HashCodes.", error: true)]
+        [EditorBrowsable(EditorBrowsableState.Never)]
+        public override bool Equals(object obj) => throw new NotSupportedException(SR.HashCode_EqualityNotSupported);
+#pragma warning restore 0809
+    }
+}