diff --git a/client/rest-high-level/src/main/java/org/elasticsearch/client/ml/datafeed/DatafeedConfig.java b/client/rest-high-level/src/main/java/org/elasticsearch/client/ml/datafeed/DatafeedConfig.java
index 84deae61f8e62..624d5960c79ad 100644
--- a/client/rest-high-level/src/main/java/org/elasticsearch/client/ml/datafeed/DatafeedConfig.java
+++ b/client/rest-high-level/src/main/java/org/elasticsearch/client/ml/datafeed/DatafeedConfig.java
@@ -286,11 +286,11 @@ public Builder(DatafeedConfig config) {
             this.jobId = config.jobId;
             this.queryDelay = config.queryDelay;
             this.frequency = config.frequency;
-            this.indices = config.indices;
-            this.types = config.types;
+            this.indices = config.indices == null ? null : new ArrayList<>(config.indices);
+            this.types = config.types == null ? null : new ArrayList<>(config.types);
             this.query = config.query;
             this.aggregations = config.aggregations;
-            this.scriptFields = config.scriptFields;
+            this.scriptFields = config.scriptFields == null ? null : new ArrayList<>(config.scriptFields);
             this.scrollSize = config.scrollSize;
             this.chunkingConfig = config.chunkingConfig;
         }
diff --git a/client/rest-high-level/src/main/java/org/elasticsearch/client/ml/job/config/Job.java b/client/rest-high-level/src/main/java/org/elasticsearch/client/ml/job/config/Job.java
index f5d6711776ec4..9f5a8001c765a 100644
--- a/client/rest-high-level/src/main/java/org/elasticsearch/client/ml/job/config/Job.java
+++ b/client/rest-high-level/src/main/java/org/elasticsearch/client/ml/job/config/Job.java
@@ -28,8 +28,10 @@
 import org.elasticsearch.common.xcontent.XContentBuilder;
 
 import java.io.IOException;
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Date;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
@@ -449,7 +451,7 @@ public Builder(String id) {
         public Builder(Job job) {
             this.id = job.getId();
             this.jobType = job.getJobType();
-            this.groups = job.getGroups();
+            this.groups = new ArrayList<>(job.getGroups());
             this.description = job.getDescription();
             this.analysisConfig = job.getAnalysisConfig();
             this.analysisLimits = job.getAnalysisLimits();
@@ -463,7 +465,7 @@ public Builder(Job job) {
             this.backgroundPersistInterval = job.getBackgroundPersistInterval();
             this.modelSnapshotRetentionDays = job.getModelSnapshotRetentionDays();
             this.resultsRetentionDays = job.getResultsRetentionDays();
-            this.customSettings = job.getCustomSettings();
+            this.customSettings = job.getCustomSettings() == null ? null : new HashMap<>(job.getCustomSettings());
             this.modelSnapshotId = job.getModelSnapshotId();
             this.resultsIndexName = job.getResultsIndexNameNoPrefix();
             this.deleting = job.getDeleting();
diff --git a/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/datafeed/DatafeedConfig.java b/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/datafeed/DatafeedConfig.java
index afe38dc29bf7f..e12f472299e73 100644
--- a/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/datafeed/DatafeedConfig.java
+++ b/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/datafeed/DatafeedConfig.java
@@ -38,6 +38,7 @@
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Comparator;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
@@ -461,14 +462,14 @@ public Builder(DatafeedConfig config) {
             this.jobId = config.jobId;
             this.queryDelay = config.queryDelay;
             this.frequency = config.frequency;
-            this.indices = config.indices;
-            this.types = config.types;
+            this.indices = new ArrayList<>(config.indices);
+            this.types = new ArrayList<>(config.types);
             this.query = config.query;
             this.aggregations = config.aggregations;
-            this.scriptFields = config.scriptFields;
+            this.scriptFields = config.scriptFields == null ? null : new ArrayList<>(config.scriptFields);
             this.scrollSize = config.scrollSize;
             this.chunkingConfig = config.chunkingConfig;
-            this.headers = config.headers;
+            this.headers = new HashMap<>(config.headers);
         }
 
         public void setId(String datafeedId) {
diff --git a/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/job/config/Job.java b/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/job/config/Job.java
index 95ba05f4dc8e4..1d0bc90101343 100644
--- a/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/job/config/Job.java
+++ b/x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/job/config/Job.java
@@ -32,6 +32,7 @@
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Date;
+import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
@@ -664,7 +665,7 @@ public Builder(Job job) {
             this.id = job.getId();
             this.jobType = job.getJobType();
             this.jobVersion = job.getJobVersion();
-            this.groups = job.getGroups();
+            this.groups = new ArrayList<>(job.getGroups());
             this.description = job.getDescription();
             this.analysisConfig = job.getAnalysisConfig();
             this.analysisLimits = job.getAnalysisLimits();
@@ -678,7 +679,7 @@ public Builder(Job job) {
             this.backgroundPersistInterval = job.getBackgroundPersistInterval();
             this.modelSnapshotRetentionDays = job.getModelSnapshotRetentionDays();
             this.resultsRetentionDays = job.getResultsRetentionDays();
-            this.customSettings = job.getCustomSettings();
+            this.customSettings = job.getCustomSettings() == null ? null : new HashMap<>(job.getCustomSettings());
             this.modelSnapshotId = job.getModelSnapshotId();
             this.resultsIndexName = job.getResultsIndexNameNoPrefix();
             this.deleting = job.isDeleting();
diff --git a/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/ml/datafeed/DatafeedConfigTests.java b/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/ml/datafeed/DatafeedConfigTests.java
index ffc13655d229c..a3cffe0dc8c4a 100644
--- a/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/ml/datafeed/DatafeedConfigTests.java
+++ b/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/ml/datafeed/DatafeedConfigTests.java
@@ -6,7 +6,6 @@
 package org.elasticsearch.xpack.core.ml.datafeed;
 
 import com.carrotsearch.randomizedtesting.generators.CodepointSetGenerator;
-
 import org.elasticsearch.ElasticsearchException;
 import org.elasticsearch.common.io.stream.NamedWriteableRegistry;
 import org.elasticsearch.common.io.stream.Writeable;
@@ -490,6 +489,13 @@ public void testDefaultFrequency_GivenAggregationsWithHistogramInterval_1_Hour()
         assertEquals(TimeValue.timeValueHours(1), datafeed.defaultFrequency(TimeValue.timeValueHours(12)));
     }
 
+    public void testCopyingDatafeedDoesNotCauseStackOverflow() {
+        DatafeedConfig datafeed = createTestInstance();
+        for (int i = 0; i < 100000; i++) {
+            datafeed = new DatafeedConfig.Builder(datafeed).build();
+        }
+    }
+
     public static String randomValidDatafeedId() {
         CodepointSetGenerator generator =  new CodepointSetGenerator("abcdefghijklmnopqrstuvwxyz".toCharArray());
         return generator.ofCodePointsLength(random(), 10, 10);
diff --git a/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/ml/job/config/JobTests.java b/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/ml/job/config/JobTests.java
index 4b4f20fe88615..b0b826cd54134 100644
--- a/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/ml/job/config/JobTests.java
+++ b/x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/ml/job/config/JobTests.java
@@ -580,6 +580,13 @@ public void testEarliestValidTimestamp_GivenDataCountsAndLatency() {
         assertThat(builder.build().earliestValidTimestamp(dataCounts), equalTo(123455789L));
     }
 
+    public void testCopyingJobDoesNotCauseStackOverflow() {
+        Job job = createRandomizedJob();
+        for (int i = 0; i < 100000; i++) {
+            job = new Job.Builder(job).build();
+        }
+    }
+
     public static Job.Builder buildJobBuilder(String id, Date date) {
         Job.Builder builder = new Job.Builder(id);
         builder.setCreateTime(date);