diff --git a/Sources/SotoCore/AWSServiceConfig.swift b/Sources/SotoCore/AWSServiceConfig.swift
index 8e0470435..0b71b9404 100644
--- a/Sources/SotoCore/AWSServiceConfig.swift
+++ b/Sources/SotoCore/AWSServiceConfig.swift
@@ -205,6 +205,9 @@ public final class AWSServiceConfig {
 
         /// Disable S3 signed chunked uploads
         public static let s3DisableChunkedUploads = Options(rawValue: 1 << 4)
+
+        /// calculate MD5 for requests with content-md5 header
+        public static let calculateMD5 = Options(rawValue: 1 << 5)
     }
 
     private init(
diff --git a/Sources/SotoCore/Doc/AWSShape.swift b/Sources/SotoCore/Doc/AWSShape.swift
index 322a1a15a..132f58639 100644
--- a/Sources/SotoCore/Doc/AWSShape.swift
+++ b/Sources/SotoCore/Doc/AWSShape.swift
@@ -218,6 +218,8 @@ public struct AWSShapeOptions: OptionSet {
     public static let rawPayload = AWSShapeOptions(rawValue: 1 << 2)
     /// Calculate MD5 of body is required
     public static let md5ChecksumRequired = AWSShapeOptions(rawValue: 1 << 3)
+    /// Request includes a MD5 checksum
+    public static let md5ChecksumHeader = AWSShapeOptions(rawValue: 1 << 4)
 }
 
 /// Root AWSShape which include a payload
diff --git a/Sources/SotoCore/Message/AWSRequest.swift b/Sources/SotoCore/Message/AWSRequest.swift
index 58e71b8bc..421d38bfb 100644
--- a/Sources/SotoCore/Message/AWSRequest.swift
+++ b/Sources/SotoCore/Message/AWSRequest.swift
@@ -289,7 +289,9 @@ extension AWSRequest {
         }
 
         /// MD5 checksum
-        if Input._options.contains(.md5ChecksumRequired),
+        let checksumRequired = Input._options.contains(.md5ChecksumRequired) ||
+            (Input._options.contains(.md5ChecksumHeader) && configuration.options.contains(.calculateMD5))
+        if checksumRequired,
            let buffer = body.asByteBuffer(byteBufferAllocator: configuration.byteBufferAllocator),
            headers["content-md5"].first == nil,
            let md5 = Self.calculateMD5(buffer)
diff --git a/Tests/SotoCoreTests/AWSRequestTests.swift b/Tests/SotoCoreTests/AWSRequestTests.swift
index b0d872d14..505b33bca 100644
--- a/Tests/SotoCoreTests/AWSRequestTests.swift
+++ b/Tests/SotoCoreTests/AWSRequestTests.swift
@@ -459,7 +459,7 @@ class AWSRequestTests: XCTestCase {
         XCTAssertFalse(body.isEmpty)
     }
 
-    func testMD5Checksum() {
+    func testRequiredMD5Checksum() {
         struct Input: AWSEncodableShape {
             static let _options: AWSShapeOptions = .md5ChecksumRequired
             let q: [String]
@@ -471,6 +471,23 @@ class AWSRequestTests: XCTestCase {
         XCTAssertEqual(request?.httpHeaders["Content-MD5"].first, "3W1MVcXgkODdv+m6VeZqdQ==")
     }
 
+    func testMD5ChecksumHeader() {
+        struct Input: AWSEncodableShape {
+            static let _options: AWSShapeOptions = .md5ChecksumHeader
+            let q: [String]
+        }
+        let input = Input(q: ["one", "two", "three", "four"])
+        let config = createServiceConfig(region: .useast2, service: "myservice", options: .calculateMD5)
+        var request: AWSRequest?
+        XCTAssertNoThrow(request = try AWSRequest(operation: "Test", path: "/", httpMethod: .GET, input: input, configuration: config))
+        XCTAssertEqual(request?.httpHeaders["Content-MD5"].first, "3W1MVcXgkODdv+m6VeZqdQ==")
+
+        let config2 = createServiceConfig(region: .useast2, service: "myservice")
+        var request2: AWSRequest?
+        XCTAssertNoThrow(request2 = try AWSRequest(operation: "Test", path: "/", httpMethod: .GET, input: input, configuration: config2))
+        XCTAssertNil(request2?.httpHeaders["Content-MD5"].first)
+    }
+
     func testMD5ChecksumSetAlready() {
         struct Input: AWSEncodableShape {
             static let _options: AWSShapeOptions = .md5ChecksumRequired