diff --git a/src/benchmarks/micro/libraries/System.IO.FileSystem/Perf.File.cs b/src/benchmarks/micro/libraries/System.IO.FileSystem/Perf.File.cs
index f1430ee8535..631903b8f2f 100644
--- a/src/benchmarks/micro/libraries/System.IO.FileSystem/Perf.File.cs
+++ b/src/benchmarks/micro/libraries/System.IO.FileSystem/Perf.File.cs
@@ -2,8 +2,11 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System.Collections.Generic;
 using System.Linq;
+using System.Threading.Tasks;
 using BenchmarkDotNet.Attributes;
+using BenchmarkDotNet.Extensions;
 using MicroBenchmarks;
 
 namespace System.IO.Tests
@@ -11,10 +14,18 @@ namespace System.IO.Tests
     [BenchmarkCategory(Categories.Libraries)]
     public class Perf_File
     {
+        private const int OneKibibyte = 1 << 10; // 1024
+        private const int HalfKibibyte = OneKibibyte >> 1;
+        private const int FourKibibytes = OneKibibyte << 2; // default Stream buffer size
+        private const int SixteenKibibytes = FourKibibytes << 2; // default Stream buffer size * 4
+        private const int OneMibibyte = OneKibibyte << 10;
+        private const int HundredMibibytes = OneMibibyte * 100;
+
         private const int DeleteteInnerIterations = 10;
         
         private string _testFilePath;
         private string[] _filesToRemove;
+        private Dictionary<int, byte[]> _userBuffers;
 
         [GlobalSetup(Target = nameof(Exists))]
         public void SetupExists()
@@ -46,5 +57,40 @@ public void Delete()
             foreach (var file in filesToRemove)
                 File.Delete(file);
         }
+
+        [GlobalSetup(Targets = new[] { nameof(WriteAllBytes), "WriteAllBytesAsync" })]
+        public void SetupWriteAllBytes()
+        {
+            _testFilePath = FileUtils.GetTestFilePath();
+            _userBuffers = new Dictionary<int, byte[]>()
+            {
+                { HalfKibibyte, ValuesGenerator.Array<byte>(HalfKibibyte) },
+                { FourKibibytes, ValuesGenerator.Array<byte>(FourKibibytes) },
+                { SixteenKibibytes, ValuesGenerator.Array<byte>(SixteenKibibytes) },
+                { OneMibibyte, ValuesGenerator.Array<byte>(OneMibibyte) },
+                { HundredMibibytes, ValuesGenerator.Array<byte>(HundredMibibytes) },
+            };
+        }
+
+        [Benchmark]
+        [Arguments(HalfKibibyte)]
+        [Arguments(FourKibibytes)]
+        [Arguments(SixteenKibibytes)]
+        [Arguments(OneMibibyte)]
+        [Arguments(HundredMibibytes)]
+        public void WriteAllBytes(int size) => File.WriteAllBytes(_testFilePath, _userBuffers[size]);
+
+#if !NETFRAMEWORK
+        [Benchmark]
+        [Arguments(HalfKibibyte)]
+        [Arguments(FourKibibytes)]
+        [Arguments(SixteenKibibytes)]
+        [Arguments(OneMibibyte)]
+        [Arguments(HundredMibibytes)]
+        public Task WriteAllBytesAsync(int size) => File.WriteAllBytesAsync(_testFilePath, _userBuffers[size]);
+#endif
+
+        [GlobalCleanup(Targets = new[] { nameof(WriteAllBytes), "WriteAllBytesAsync" })]
+        public void CleanupWriteAllBytes() => File.Delete(_testFilePath);
     }
 }