diff --git a/docs/src/test/java/org/elasticsearch/smoketest/DocsClientYamlTestSuiteIT.java b/docs/src/test/java/org/elasticsearch/smoketest/DocsClientYamlTestSuiteIT.java
index a79730339e3..628c364d455 100644
--- a/docs/src/test/java/org/elasticsearch/smoketest/DocsClientYamlTestSuiteIT.java
+++ b/docs/src/test/java/org/elasticsearch/smoketest/DocsClientYamlTestSuiteIT.java
@@ -48,5 +48,10 @@ public class DocsClientYamlTestSuiteIT extends ESClientYamlSuiteTestCase {
         logger.error("This failing test was generated by documentation starting at {}. It may include many snippets. "
                 + "See docs/README.asciidoc for an explanation of test generation.", name);
     }
+
+    @Override
+    protected boolean randomizeContentType() {
+        return false;
+    }
 }
 
diff --git a/qa/backwards-5.0/src/test/java/org/elasticsearch/backwards/Backwards50ClientYamlTestSuiteIT.java b/qa/backwards-5.0/src/test/java/org/elasticsearch/backwards/Backwards50ClientYamlTestSuiteIT.java
index cac063fce78..f6cb67f92fb 100644
--- a/qa/backwards-5.0/src/test/java/org/elasticsearch/backwards/Backwards50ClientYamlTestSuiteIT.java
+++ b/qa/backwards-5.0/src/test/java/org/elasticsearch/backwards/Backwards50ClientYamlTestSuiteIT.java
@@ -39,5 +39,10 @@ public class Backwards50ClientYamlTestSuiteIT extends ESClientYamlSuiteTestCase
     public static Iterable<Object[]> parameters() throws IOException {
         return createParameters();
     }
+
+    @Override
+    protected boolean randomizeContentType() {
+        return false;
+    }
 }
 
diff --git a/test/framework/src/main/java/org/elasticsearch/test/rest/yaml/ClientYamlTestExecutionContext.java b/test/framework/src/main/java/org/elasticsearch/test/rest/yaml/ClientYamlTestExecutionContext.java
index fe397f512c5..a2e03a063cf 100644
--- a/test/framework/src/main/java/org/elasticsearch/test/rest/yaml/ClientYamlTestExecutionContext.java
+++ b/test/framework/src/main/java/org/elasticsearch/test/rest/yaml/ClientYamlTestExecutionContext.java
@@ -18,15 +18,21 @@
  */
 package org.elasticsearch.test.rest.yaml;
 
+import com.carrotsearch.randomizedtesting.RandomizedTest;
 import org.apache.http.HttpEntity;
+import org.apache.http.entity.ByteArrayEntity;
 import org.apache.http.entity.ContentType;
-import org.apache.http.entity.StringEntity;
 import org.apache.logging.log4j.Logger;
+import org.apache.lucene.util.BytesRef;
 import org.elasticsearch.Version;
 import org.elasticsearch.common.logging.Loggers;
+import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentFactory;
+import org.elasticsearch.common.xcontent.XContentType;
 
 import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -41,13 +47,18 @@ public class ClientYamlTestExecutionContext {
 
     private static final Logger logger = Loggers.getLogger(ClientYamlTestExecutionContext.class);
 
+    private static final XContentType[] STREAMING_CONTENT_TYPES = new XContentType[]{XContentType.JSON, XContentType.SMILE};
+
     private final Stash stash = new Stash();
     private final ClientYamlTestClient clientYamlTestClient;
 
     private ClientYamlTestResponse response;
 
-    public ClientYamlTestExecutionContext(ClientYamlTestClient clientYamlTestClient) {
+    private final boolean randomizeContentType;
+
+    public ClientYamlTestExecutionContext(ClientYamlTestClient clientYamlTestClient, boolean randomizeContentType) {
         this.clientYamlTestClient = clientYamlTestClient;
+        this.randomizeContentType = randomizeContentType;
     }
 
     /**
@@ -65,7 +76,7 @@ public class ClientYamlTestExecutionContext {
             }
         }
 
-        HttpEntity entity = createEntity(bodies);
+        HttpEntity entity = createEntity(bodies, headers);
         try {
             response = callApiInternal(apiName, requestParams, entity, headers);
             return response;
@@ -80,23 +91,56 @@ public class ClientYamlTestExecutionContext {
         }
     }
 
-    private HttpEntity createEntity(List<Map<String, Object>> bodies) throws IOException {
+    private HttpEntity createEntity(List<Map<String, Object>> bodies, Map<String, String> headers) throws IOException {
         if (bodies.isEmpty()) {
             return null;
         }
         if (bodies.size() == 1) {
-            String bodyAsString = bodyAsString(stash.replaceStashedValues(bodies.get(0)));
-            return new StringEntity(bodyAsString, ContentType.APPLICATION_JSON);
+            XContentType xContentType = getContentType(headers, XContentType.values());
+            BytesRef bytesRef = bodyAsBytesRef(bodies.get(0), xContentType);
+            return new ByteArrayEntity(bytesRef.bytes, bytesRef.offset, bytesRef.length,
+                    ContentType.create(xContentType.mediaTypeWithoutParameters(), StandardCharsets.UTF_8));
+        } else {
+            XContentType xContentType = getContentType(headers, STREAMING_CONTENT_TYPES);
+            List<BytesRef> bytesRefList = new ArrayList<>();
+            int totalBytesLength = 0;
+            for (Map<String, Object> body : bodies) {
+                BytesRef bytesRef = bodyAsBytesRef(body, xContentType);
+                bytesRefList.add(bytesRef);
+                totalBytesLength += bytesRef.length - bytesRef.offset + 1;
+            }
+            byte[] bytes = new byte[totalBytesLength];
+            int position = 0;
+            for (BytesRef bytesRef : bytesRefList) {
+                for (int i = bytesRef.offset; i < bytesRef.length; i++) {
+                    bytes[position++] = bytesRef.bytes[i];
+                }
+                bytes[position++] = xContentType.xContent().streamSeparator();
+            }
+            return new ByteArrayEntity(bytes, ContentType.create(xContentType.mediaTypeWithoutParameters(), StandardCharsets.UTF_8));
         }
-        StringBuilder bodyBuilder = new StringBuilder();
-        for (Map<String, Object> body : bodies) {
-            bodyBuilder.append(bodyAsString(stash.replaceStashedValues(body))).append("\n");
-        }
-        return new StringEntity(bodyBuilder.toString(), ContentType.APPLICATION_JSON);
     }
 
-    private String bodyAsString(Map<String, Object> body) throws IOException {
-        return XContentFactory.jsonBuilder().map(body).string();
+    private XContentType getContentType(Map<String, String> headers, XContentType[] supportedContentTypes) {
+        XContentType xContentType = null;
+        String contentType = headers.get("Content-Type");
+        if (contentType != null) {
+            xContentType = XContentType.fromMediaType(contentType);
+        }
+        if (xContentType != null) {
+            return xContentType;
+        }
+        if (randomizeContentType) {
+            return RandomizedTest.randomFrom(supportedContentTypes);
+        }
+        return XContentType.JSON;
+    }
+
+    private BytesRef bodyAsBytesRef(Map<String, Object> bodyAsMap, XContentType xContentType) throws IOException {
+        Map<String, Object> finalBodyAsMap = stash.replaceStashedValues(bodyAsMap);
+        try (XContentBuilder builder = XContentFactory.contentBuilder(xContentType)) {
+            return builder.map(finalBodyAsMap).bytes().toBytesRef();
+        }
     }
 
     private ClientYamlTestResponse callApiInternal(String apiName, Map<String, String> params,
diff --git a/test/framework/src/main/java/org/elasticsearch/test/rest/yaml/ESClientYamlSuiteTestCase.java b/test/framework/src/main/java/org/elasticsearch/test/rest/yaml/ESClientYamlSuiteTestCase.java
index b64f12e9f02..32436515fe8 100644
--- a/test/framework/src/main/java/org/elasticsearch/test/rest/yaml/ESClientYamlSuiteTestCase.java
+++ b/test/framework/src/main/java/org/elasticsearch/test/rest/yaml/ESClientYamlSuiteTestCase.java
@@ -145,8 +145,8 @@ public abstract class ESClientYamlSuiteTestCase extends ESRestTestCase {
             }
             ClientYamlTestClient clientYamlTestClient =
                 new ClientYamlTestClient(restSpec, restClient, hosts, esVersion);
-            restTestExecutionContext = new ClientYamlTestExecutionContext(clientYamlTestClient);
-            adminExecutionContext = new ClientYamlTestExecutionContext(clientYamlTestClient);
+            restTestExecutionContext = new ClientYamlTestExecutionContext(clientYamlTestClient, randomizeContentType());
+            adminExecutionContext = new ClientYamlTestExecutionContext(clientYamlTestClient, false);
             String[] blacklist = resolvePathsProperty(REST_TESTS_BLACKLIST, null);
             blacklistPathMatchers = new ArrayList<>();
             for (String entry : blacklist) {
@@ -381,4 +381,8 @@ public abstract class ESClientYamlSuiteTestCase extends ESRestTestCase {
     private String errorMessage(ExecutableSection executableSection, Throwable t) {
         return "Failure at [" + testCandidate.getSuitePath() + ":" + executableSection.getLocation().lineNumber + "]: " + t.getMessage();
     }
+
+    protected boolean randomizeContentType() {
+        return true;
+    }
 }