diff --git a/csharp/src/Google.Protobuf.Benchmarks/ParseMessagesBenchmark.cs b/csharp/src/Google.Protobuf.Benchmarks/ParseMessagesBenchmark.cs
index 30f3e9ef37..4152b9fed2 100644
--- a/csharp/src/Google.Protobuf.Benchmarks/ParseMessagesBenchmark.cs
+++ b/csharp/src/Google.Protobuf.Benchmarks/ParseMessagesBenchmark.cs
@@ -123,7 +123,7 @@ namespace Google.Protobuf.Benchmarks
             manyPrimitiveFieldsTest.ParseDelimitedMessagesFromReadOnlySequence(messageCount);
         }
 
-        private static ManyWrapperFieldsMessage CreateManyWrapperFieldsMessage()
+        public static ManyWrapperFieldsMessage CreateManyWrapperFieldsMessage()
         {
             // Example data match data of an internal benchmarks
             return new ManyWrapperFieldsMessage()
@@ -140,7 +140,7 @@ namespace Google.Protobuf.Benchmarks
             };
         }
 
-        private static ManyPrimitiveFieldsMessage CreateManyPrimitiveFieldsMessage()
+        public static ManyPrimitiveFieldsMessage CreateManyPrimitiveFieldsMessage()
         {
             // Example data match data of an internal benchmarks
             return new ManyPrimitiveFieldsMessage()
diff --git a/csharp/src/Google.Protobuf.Benchmarks/WriteMessagesBenchmark.cs b/csharp/src/Google.Protobuf.Benchmarks/WriteMessagesBenchmark.cs
new file mode 100644
index 0000000000..5a3bba74d2
--- /dev/null
+++ b/csharp/src/Google.Protobuf.Benchmarks/WriteMessagesBenchmark.cs
@@ -0,0 +1,198 @@
+#region Copyright notice and license
+// Protocol Buffers - Google's data interchange format
+// Copyright 2019 Google Inc.  All rights reserved.
+// https://github.com/protocolbuffers/protobuf
+//
+// 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.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// 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.
+#endregion
+
+using BenchmarkDotNet.Attributes;
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Buffers;
+using Google.Protobuf.WellKnownTypes;
+
+namespace Google.Protobuf.Benchmarks
+{
+    /// <summary>
+    /// Benchmark that tests writing performance for various messages.
+    /// </summary>
+    [MemoryDiagnoser]
+    public class WriteMessagesBenchmark
+    {
+        const int MaxMessages = 100;
+
+        SubTest manyWrapperFieldsTest = new SubTest(ParseMessagesBenchmark.CreateManyWrapperFieldsMessage(), MaxMessages);
+        SubTest manyPrimitiveFieldsTest = new SubTest(ParseMessagesBenchmark.CreateManyPrimitiveFieldsMessage(), MaxMessages);
+        SubTest emptyMessageTest = new SubTest(new Empty(), MaxMessages);
+
+        public IEnumerable<int> MessageCountValues => new[] { 10, 100 };
+
+        [GlobalSetup]
+        public void GlobalSetup()
+        {
+        }
+
+        [Benchmark]
+        public byte[] ManyWrapperFieldsMessage_ToByteArray()
+        {
+            return manyWrapperFieldsTest.ToByteArray();
+        }
+
+        [Benchmark]
+        public byte[] ManyWrapperFieldsMessage_WriteToCodedOutputStream()
+        {
+            return manyWrapperFieldsTest.WriteToCodedOutputStream_PreAllocatedBuffer();
+        }
+
+        [Benchmark]
+        public byte[] ManyWrapperFieldsMessage_WriteToSpan()
+        {
+            return manyWrapperFieldsTest.WriteToSpan_PreAllocatedBuffer();
+        }
+
+
+        [Benchmark]
+        public byte[] ManyPrimitiveFieldsMessage_ToByteArray()
+        {
+            return manyPrimitiveFieldsTest.ToByteArray();
+        }
+
+        [Benchmark]
+        public byte[] ManyPrimitiveFieldsMessage_WriteToCodedOutputStream()
+        {
+            return manyPrimitiveFieldsTest.WriteToCodedOutputStream_PreAllocatedBuffer();
+        }
+
+        [Benchmark]
+        public byte[] ManyPrimitiveFieldsMessage_WriteToSpan()
+        {
+            return manyPrimitiveFieldsTest.WriteToSpan_PreAllocatedBuffer();
+        }
+
+        [Benchmark]
+        public byte[] EmptyMessage_ToByteArray()
+        {
+            return emptyMessageTest.ToByteArray();
+        }
+
+        [Benchmark]
+        public byte[] EmptyMessage_WriteToCodedOutputStream()
+        {
+            return emptyMessageTest.WriteToCodedOutputStream_PreAllocatedBuffer();
+        }
+
+        [Benchmark]
+        public byte[] EmptyMessage_WriteToSpan()
+        {
+            return emptyMessageTest.WriteToSpan_PreAllocatedBuffer();
+        }
+
+        [Benchmark]
+        [ArgumentsSource(nameof(MessageCountValues))]
+        public void ManyWrapperFieldsMessage_WriteDelimitedMessagesToCodedOutputStream(int messageCount)
+        {
+            manyWrapperFieldsTest.WriteDelimitedMessagesToCodedOutputStream_PreAllocatedBuffer(messageCount);
+        }
+
+        [Benchmark]
+        [ArgumentsSource(nameof(MessageCountValues))]
+        public void ManyWrapperFieldsMessage_WriteDelimitedMessagesToSpan(int messageCount)
+        {
+            manyWrapperFieldsTest.WriteDelimitedMessagesToSpan_PreAllocatedBuffer(messageCount);
+        }
+
+        [Benchmark]
+        [ArgumentsSource(nameof(MessageCountValues))]
+        public void ManyPrimitiveFieldsMessage_WriteDelimitedMessagesToCodedOutputStream(int messageCount)
+        {
+            manyPrimitiveFieldsTest.WriteDelimitedMessagesToCodedOutputStream_PreAllocatedBuffer(messageCount);
+        }
+
+        [Benchmark]
+        [ArgumentsSource(nameof(MessageCountValues))]
+        public void ManyPrimitiveFieldsMessage_WriteDelimitedMessagesToSpan(int messageCount)
+        {
+            manyPrimitiveFieldsTest.WriteDelimitedMessagesToSpan_PreAllocatedBuffer(messageCount);
+        }
+
+        private class SubTest
+        {
+            private readonly IMessage message;
+            private readonly byte[] outputBuffer;
+            private readonly byte[] multipleMessagesOutputBuffer;
+
+            public SubTest(IMessage message, int maxMessageCount)
+            {
+                this.message = message;
+
+                int messageSize = message.CalculateSize();
+                this.outputBuffer = new byte[messageSize];
+                this.multipleMessagesOutputBuffer = new byte[maxMessageCount * (messageSize + CodedOutputStream.ComputeLengthSize(messageSize))];
+            }
+
+            public byte[] ToByteArray() => message.ToByteArray();
+
+            public byte[] WriteToCodedOutputStream_PreAllocatedBuffer()
+            {
+                var cos = new CodedOutputStream(outputBuffer);  // use pre-existing output buffer
+                message.WriteTo(cos);
+                return outputBuffer;
+            }
+
+            public byte[] WriteToSpan_PreAllocatedBuffer()
+            {
+                var span = new Span<byte>(outputBuffer);  // use pre-existing output buffer
+                message.WriteTo(span);
+                return outputBuffer;
+            }
+
+            public byte[] WriteDelimitedMessagesToCodedOutputStream_PreAllocatedBuffer(int messageCount)
+            {
+                var cos = new CodedOutputStream(multipleMessagesOutputBuffer);  // use pre-existing output buffer
+                for (int i = 0; i < messageCount; i++)
+                {
+                    cos.WriteMessage(message);
+                }
+                return multipleMessagesOutputBuffer;
+            }
+
+            public byte[] WriteDelimitedMessagesToSpan_PreAllocatedBuffer(int messageCount)
+            {
+                var span = new Span<byte>(multipleMessagesOutputBuffer);  // use pre-existing output buffer
+                WriteContext.Initialize(ref span, out WriteContext ctx);
+                for (int i = 0; i < messageCount; i++)
+                {
+                    ctx.WriteMessage(message);
+                }
+                return multipleMessagesOutputBuffer;
+            }
+        }
+    }
+}