diff --git a/hadoop-mapreduce-project/CHANGES.txt b/hadoop-mapreduce-project/CHANGES.txt
index 7a2bf0f7b61..5ed76a70e00 100644
--- a/hadoop-mapreduce-project/CHANGES.txt
+++ b/hadoop-mapreduce-project/CHANGES.txt
@@ -130,6 +130,9 @@ Release 2.1.1-beta - UNRELEASED
     MAPREDUCE-5164. mapred job and queue commands omit HADOOP_CLIENT_OPTS 
     (Nemon Lou via devaraj)
 
+    MAPREDUCE-5493. Cleanup in-memory & on-disk segments to prevent leak on
+    shuffle completion. (jlowe via acmurthy)
+
 Release 2.1.0-beta - 2013-08-22
 
   INCOMPATIBLE CHANGES
diff --git a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/MergeManagerImpl.java b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/MergeManagerImpl.java
index e52f4bf6593..ca3bed93998 100644
--- a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/MergeManagerImpl.java
+++ b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/MergeManagerImpl.java
@@ -355,8 +355,11 @@ public class MergeManagerImpl<K, V> implements MergeManager<K, V> {
     
     List<InMemoryMapOutput<K, V>> memory = 
       new ArrayList<InMemoryMapOutput<K, V>>(inMemoryMergedMapOutputs);
+    inMemoryMergedMapOutputs.clear();
     memory.addAll(inMemoryMapOutputs);
+    inMemoryMapOutputs.clear();
     List<CompressAwarePath> disk = new ArrayList<CompressAwarePath>(onDiskMapOutputs);
+    onDiskMapOutputs.clear();
     return finalMerge(jobConf, rfs, memory, disk);
   }
    
diff --git a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/test/java/org/apache/hadoop/mapreduce/task/reduce/TestMerger.java b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/test/java/org/apache/hadoop/mapreduce/task/reduce/TestMerger.java
index 41a1848c35f..f1d54359b82 100644
--- a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/test/java/org/apache/hadoop/mapreduce/task/reduce/TestMerger.java
+++ b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/test/java/org/apache/hadoop/mapreduce/task/reduce/TestMerger.java
@@ -82,7 +82,7 @@ public class TestMerger {
   }
   
   @Test
-  public void testInMemoryMerger() throws IOException {
+  public void testInMemoryMerger() throws Throwable {
     JobID jobId = new JobID("a", 0);
     TaskAttemptID reduceId = new TaskAttemptID(
         new TaskID(jobId, TaskType.REDUCE, 0), 0);
@@ -132,6 +132,11 @@ public class TestMerger {
     readOnDiskMapOutput(conf, fs, outPath, keys, values);
     Assert.assertEquals(keys, Arrays.asList("apple", "banana", "carrot"));
     Assert.assertEquals(values, Arrays.asList("disgusting", "pretty good", "delicious"));
+
+    mergeManager.close();
+    Assert.assertEquals(0, mergeManager.inMemoryMapOutputs.size());
+    Assert.assertEquals(0, mergeManager.inMemoryMergedMapOutputs.size());
+    Assert.assertEquals(0, mergeManager.onDiskMapOutputs.size());
   }
   
   private byte[] writeMapOutput(Configuration conf, Map<String, String> keysToValues)