diff --git a/codegen/sdk-codegen/aws-models-test/s3/s3-tests.smithy b/codegen/sdk-codegen/aws-models-test/s3/s3-tests.smithy
new file mode 100644
index 00000000000..898b90fc88b
--- /dev/null
+++ b/codegen/sdk-codegen/aws-models-test/s3/s3-tests.smithy
@@ -0,0 +1,65 @@
+$version: "1.0"
+
+namespace com.amazonaws.s3
+use smithy.test#httpResponseTests
+use smithy.test#httpRequestTests
+
+apply NotFound @httpResponseTests([
+    {
+        id: "HeadObjectEmptyBody",
+        documentation: "This test case validates https://github.com/awslabs/aws-sdk-swift/issues/183",
+        params: {
+        },
+        body: "",
+        protocol: "aws.protocols#restXml",
+        code: 404,
+        headers: {
+            "x-amz-request-id": "GRZ6BZ468DF52F2E",
+            "x-amz-id-2": "UTniwu6QmCIjVeuK2ZfeWBOnu7SqMQOS3Vac6B/K4H2ZCawYUl+nDbhGTImuyhZ5DFiojR3Kcz4=",
+            "content-type": "application/xml",
+            "date": "Thu, 03 Jun 2021 04:05:52 GMT",
+            "server": "AmazonS3"
+        }
+    }
+])
+
+// FIXME - when we implement virtual host addressing as the default will need to change the host and uri
+//         see: https://github.com/awslabs/aws-sdk-kotlin/issues/220
+apply PutObject @httpRequestTests([
+    {
+        id: "PutObjectDefaultContentType",
+        documentation: "This test case validates default content-type behavior when not specified in the request",
+        protocol: "aws.protocols#restXml",
+        method: "PUT",
+        uri: "/mybucket/mykey",
+        host: "s3.us-west-2.amazonaws.com",
+        body: "foobar",
+        bodyMediaType: "application/octet-stream",
+        headers: {
+            "Content-Type": "application/octet-stream"
+        },
+        params: {
+            Bucket: "mybucket",
+            Key: "mykey",
+            Body: "foobar"
+        }
+    },
+    {
+        id: "PutOtTbjectExplicitContenype",
+        documentation: "This test case validates https://github.com/awslabs/aws-sdk-kotlin/issues/193",
+        protocol: "aws.protocols#restXml",
+        method: "PUT",
+        uri: "/mybucket/mykey",
+        host: "s3.us-west-2.amazonaws.com",
+        body: "{\"foo\":\"bar\"}",
+        headers: {
+            "Content-Type": "application/json"
+        },
+        params: {
+            Bucket: "mybucket",
+            Key: "mykey",
+            ContentType: "application/json",
+            Body: "{\"foo\":\"bar\"}"
+        }
+    }
+])
\ No newline at end of file
diff --git a/codegen/sdk-codegen/build.gradle.kts b/codegen/sdk-codegen/build.gradle.kts
index 1d85b177d80..60d1d52e9cc 100644
--- a/codegen/sdk-codegen/build.gradle.kts
+++ b/codegen/sdk-codegen/build.gradle.kts
@@ -78,13 +78,21 @@ data class AwsService(
 // The generated smithy-build.json file is not committed to git since
 // it's rebuilt each time codegen is performed.
 fun generateSmithyBuild(services: List<AwsService>): String {
+    require(services.isNotEmpty()) {
+        "No services discovered. Verify aws.services and aws.protocols properties in local.build. Aborting."
+    }
     val buildStandaloneSdk = getProperty("buildStandaloneSdk")?.toBoolean() ?: false
     val projections = services.joinToString(",") { service ->
         // escape windows paths for valid json
         val absModelPath = service.modelFile.absolutePath.replace("\\", "\\\\")
+        val importPaths = mutableListOf(absModelPath)
+        if (file(service.modelExtrasDir).exists()) {
+            importPaths.add(service.modelExtrasDir.replace("\\", "\\\\"))
+        }
+        val imports = importPaths.joinToString { "\"$it\"" }
         """
             "${service.projectionName}": {
-                "imports": ["$absModelPath"],
+                "imports": [$imports],
                 "plugins": {
                     "swift-codegen": {
                       "service": "${service.name}",
@@ -168,6 +176,12 @@ val AwsService.destinationDir: String
         return rootProject.file("release").absolutePath
     }
 
+val AwsService.modelExtrasDir: String
+    get() {
+        val sanitizedName = projectionName.split(".")[0]
+        return rootProject.file("codegen/sdk-codegen/aws-models-test/${sanitizedName}").absolutePath
+    }
+
 task("stageSdks") {
     group = "codegen"
     description = "relocate generated SDK(s) from build directory to release dir"