diff --git a/hadoop-mapreduce-project/CHANGES.txt b/hadoop-mapreduce-project/CHANGES.txt
index 8ca1299e6b5..07fde4f4c6a 100644
--- a/hadoop-mapreduce-project/CHANGES.txt
+++ b/hadoop-mapreduce-project/CHANGES.txt
@@ -505,6 +505,9 @@ Release 0.23.3 - UNRELEASED
 
     MAPREDUCE-4267. mavenize pipes (tgraves via bobby)
 
+    MAPREDUCE-4375. Show Configuration Tracability in MR UI (bobby 
+    via tgraves)
+
   OPTIMIZATIONS
 
     MAPREDUCE-3850. Avoid redundant calls for tokens in TokenCache (Daryn
diff --git a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/job/impl/JobImpl.java b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/job/impl/JobImpl.java
index 10eb68dbf85..982c89c4c94 100644
--- a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/job/impl/JobImpl.java
+++ b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/job/impl/JobImpl.java
@@ -1561,7 +1561,7 @@ public Configuration loadConfFile() throws IOException {
     Path confPath = getConfFile();
     FileContext fc = FileContext.getFileContext(confPath.toUri(), conf);
     Configuration jobConf = new Configuration(false);
-    jobConf.addResource(fc.open(confPath));
+    jobConf.addResource(fc.open(confPath), confPath.toString());
     return jobConf;
   }
 }
diff --git a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/webapp/ConfBlock.java b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/webapp/ConfBlock.java
index 36f202e66bf..fd2edb45701 100644
--- a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/webapp/ConfBlock.java
+++ b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/webapp/ConfBlock.java
@@ -78,14 +78,29 @@ public class ConfBlock extends HtmlBlock {
           tr().
             th(_TH, "key").
             th(_TH, "value").
+            th(_TH, "source chain").
           _().
         _().
       tbody();
       for (ConfEntryInfo entry : info.getProperties()) {
+        StringBuffer buffer = new StringBuffer();
+        String[] sources = entry.getSource();
+        //Skip the last entry, because it is always the same HDFS file, and
+        // output them in reverse order so most recent is output first
+        boolean first = true;
+        for(int i = (sources.length  - 2); i >= 0; i--) {
+          if(!first) {
+            // \u2B05 is an arrow <--
+            buffer.append(" \u2B05 ");
+          }
+          first = false;
+          buffer.append(sources[i]);
+        }
         tbody.
           tr().
             td(entry.getName()).
             td(entry.getValue()).
+            td(buffer.toString()).
           _();
       }
       tbody._().
@@ -93,6 +108,7 @@ public class ConfBlock extends HtmlBlock {
         tr().
           th().input("search_init").$type(InputType.text).$name("key").$value("key")._()._().
           th().input("search_init").$type(InputType.text).$name("value").$value("value")._()._().
+          th().input("search_init").$type(InputType.text).$name("source chain").$value("source chain")._()._().
           _().
         _().
       _();
diff --git a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/webapp/dao/ConfEntryInfo.java b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/webapp/dao/ConfEntryInfo.java
index 5cfa40aa1aa..bfd50ef0db4 100644
--- a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/webapp/dao/ConfEntryInfo.java
+++ b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/webapp/dao/ConfEntryInfo.java
@@ -27,13 +27,19 @@ public class ConfEntryInfo {
 
   protected String name;
   protected String value;
+  protected String[] source;
 
   public ConfEntryInfo() {
   }
 
   public ConfEntryInfo(String key, String value) {
+    this(key, value, null);
+  }
+  
+  public ConfEntryInfo(String key, String value, String[] source) {
     this.name = key;
     this.value = value;
+    this.source = source;
   }
 
   public String getName() {
@@ -43,4 +49,8 @@ public String getName() {
   public String getValue() {
     return this.value;
   }
+  
+  public String[] getSource() {
+    return source;
+  }
 }
diff --git a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/webapp/dao/ConfInfo.java b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/webapp/dao/ConfInfo.java
index fa971a749e4..a05c3176f9c 100644
--- a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/webapp/dao/ConfInfo.java
+++ b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/main/java/org/apache/hadoop/mapreduce/v2/app/webapp/dao/ConfInfo.java
@@ -46,7 +46,8 @@ public ConfInfo(Job job) throws IOException {
     Configuration jobConf = job.loadConfFile();
     this.path = job.getConfFile().toString();
     for (Map.Entry<String, String> entry : jobConf) {
-      this.property.add(new ConfEntryInfo(entry.getKey(), entry.getValue()));
+      this.property.add(new ConfEntryInfo(entry.getKey(), entry.getValue(), 
+          jobConf.getPropertySources(entry.getKey())));
     }
 
   }
diff --git a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/test/java/org/apache/hadoop/mapreduce/v2/app/MockJobs.java b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/test/java/org/apache/hadoop/mapreduce/v2/app/MockJobs.java
index 7f1d8200327..a9e4e4910c0 100644
--- a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/test/java/org/apache/hadoop/mapreduce/v2/app/MockJobs.java
+++ b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-app/src/test/java/org/apache/hadoop/mapreduce/v2/app/MockJobs.java
@@ -603,7 +603,7 @@ public List<AMInfo> getAMInfos() {
       public Configuration loadConfFile() throws IOException {
         FileContext fc = FileContext.getFileContext(configFile.toUri(), conf);
         Configuration jobConf = new Configuration(false);
-        jobConf.addResource(fc.open(configFile));
+        jobConf.addResource(fc.open(configFile), configFile.toString());
         return jobConf;
       }
     };
diff --git a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-hs/src/main/java/org/apache/hadoop/mapreduce/v2/hs/HistoryFileManager.java b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-hs/src/main/java/org/apache/hadoop/mapreduce/v2/hs/HistoryFileManager.java
index 6447109916b..743dc0920a9 100644
--- a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-hs/src/main/java/org/apache/hadoop/mapreduce/v2/hs/HistoryFileManager.java
+++ b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-hs/src/main/java/org/apache/hadoop/mapreduce/v2/hs/HistoryFileManager.java
@@ -336,7 +336,7 @@ public synchronized Path getConfFile() {
     public synchronized Configuration loadConfFile() throws IOException {
       FileContext fc = FileContext.getFileContext(confFile.toUri(), conf);
       Configuration jobConf = new Configuration(false);
-      jobConf.addResource(fc.open(confFile));
+      jobConf.addResource(fc.open(confFile), confFile.toString());
       return jobConf;
     }
   }
diff --git a/hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/HistoryServerRest.apt.vm b/hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/HistoryServerRest.apt.vm
index de51c8ad3fb..5b11736b8fe 100644
--- a/hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/HistoryServerRest.apt.vm
+++ b/hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/HistoryServerRest.apt.vm
@@ -1261,6 +1261,9 @@ History Server REST API's.
 *---------------+--------------+-------------------------------+
 | value | string | The value of the configuration property |
 *---------------+--------------+-------------------------------+
+| source | string | The location this configuration object came from. If there is more then one of these it shows the history with the latest source at the end of the list. |
+*---------------+--------------+-------------------------------+
+
 
 *** Response Examples
 
@@ -1293,14 +1296,17 @@ History Server REST API's.
          {  
             "value" : "/home/hadoop/hdfs/data",
             "name" : "dfs.datanode.data.dir"
+            "source" : ["hdfs-site.xml", "job.xml"]
          },
          {
             "value" : "org.apache.hadoop.yarn.server.webproxy.amfilter.AmFilterInitializer",
             "name" : "hadoop.http.filter.initializers"
+            "source" : ["programatically", "job.xml"]
          },
          {
             "value" : "/home/hadoop/tmp",
             "name" : "mapreduce.cluster.temp.dir"
+            "source" : ["mapred-site.xml"]
          },
          ...
       ]
@@ -1335,14 +1341,19 @@ History Server REST API's.
   <property>
     <name>dfs.datanode.data.dir</name>
     <value>/home/hadoop/hdfs/data</value>
+    <source>hdfs-site.xml</source>
+    <source>job.xml</source>
   </property>
   <property>
     <name>hadoop.http.filter.initializers</name>
     <value>org.apache.hadoop.yarn.server.webproxy.amfilter.AmFilterInitializer</value>
+    <source>programatically</source>
+    <source>job.xml</source>
   </property>
   <property>
     <name>mapreduce.cluster.temp.dir</name>
     <value>/home/hadoop/tmp</value>
+    <source>mapred-site.xml</source>
   </property>
   ...
 </conf>
diff --git a/hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/MapredAppMasterRest.apt.vm b/hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/MapredAppMasterRest.apt.vm
index ffd25c4763f..de0093c269c 100644
--- a/hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/MapredAppMasterRest.apt.vm
+++ b/hadoop-mapreduce-project/hadoop-yarn/hadoop-yarn-site/src/site/apt/MapredAppMasterRest.apt.vm
@@ -1296,6 +1296,8 @@ MapReduce Application Master REST API's.
 *---------------+--------------+-------------------------------+
 | value | string | The value of the configuration property |
 *---------------+--------------+-------------------------------+
+| source | string | The location this configuration object came from. If there is more then one of these it shows the history with the latest source at the end of the list. |
+*---------------+--------------+-------------------------------+
 
 ** Response Examples
 
@@ -1327,15 +1329,18 @@ MapReduce Application Master REST API's.
       "property" : [
          {  
             "value" : "/home/hadoop/hdfs/data",
-            "name" : "dfs.datanode.data.dir"
+            "name" : "dfs.datanode.data.dir",
+            "source" : ["hdfs-site.xml", "job.xml"]
          },
          {
             "value" : "org.apache.hadoop.yarn.server.webproxy.amfilter.AmFilterInitializer",
             "name" : "hadoop.http.filter.initializers"
+            "source" : ["programatically", "job.xml"]
          },
          {
             "value" : "/home/hadoop/tmp",
             "name" : "mapreduce.cluster.temp.dir"
+            "source" : ["mapred-site.xml"]
          },
          ...
       ]
@@ -1370,14 +1375,19 @@ MapReduce Application Master REST API's.
   <property>
     <name>dfs.datanode.data.dir</name>
     <value>/home/hadoop/hdfs/data</value>
+    <source>hdfs-site.xml</source>
+    <source>job.xml</source>
   </property>
   <property>
     <name>hadoop.http.filter.initializers</name>
     <value>org.apache.hadoop.yarn.server.webproxy.amfilter.AmFilterInitializer</value>
+    <source>programatically</source>
+    <source>job.xml</source>
   </property>
   <property>
     <name>mapreduce.cluster.temp.dir</name>
     <value>/home/hadoop/tmp</value>
+    <source>mapred-site.xml</source>
   </property>
   ...
 </conf>