diff --git a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/RunJar.java b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/RunJar.java
index 9dd770c43a..f1b643c4b0 100644
--- a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/RunJar.java
+++ b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/RunJar.java
@@ -76,7 +76,11 @@ public class RunJar {
    */
   public static final String HADOOP_CLIENT_CLASSLOADER_SYSTEM_CLASSES =
       "HADOOP_CLIENT_CLASSLOADER_SYSTEM_CLASSES";
-
+  /**
+   * Environment key for disabling unjar in client code.
+   */
+  public static final String HADOOP_CLIENT_SKIP_UNJAR =
+      "HADOOP_CLIENT_SKIP_UNJAR";
   /**
    * Buffer size for copy the content of compressed file to new file.
    */
@@ -93,7 +97,7 @@ public class RunJar {
    * @throws IOException if an I/O error has occurred or toDir
    * cannot be created and does not already exist
    */
-  public static void unJar(File jarFile, File toDir) throws IOException {
+  public void unJar(File jarFile, File toDir) throws IOException {
     unJar(jarFile, toDir, MATCH_ANY);
   }
 
@@ -292,8 +296,9 @@ public void run() {
           }
         }, SHUTDOWN_HOOK_PRIORITY);
 
-
-    unJar(file, workDir);
+    if (!skipUnjar()) {
+      unJar(file, workDir);
+    }
 
     ClassLoader loader = createClassLoader(file, workDir);
 
@@ -364,6 +369,10 @@ boolean useClientClassLoader() {
     return Boolean.parseBoolean(System.getenv(HADOOP_USE_CLIENT_CLASSLOADER));
   }
 
+  boolean skipUnjar() {
+    return Boolean.parseBoolean(System.getenv(HADOOP_CLIENT_SKIP_UNJAR));
+  }
+
   String getHadoopClasspath() {
     return System.getenv(HADOOP_CLASSPATH);
   }
diff --git a/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestRunJar.java b/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestRunJar.java
index 19485d69e8..ea07b970a2 100644
--- a/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestRunJar.java
+++ b/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestRunJar.java
@@ -17,10 +17,14 @@
  */
 package org.apache.hadoop.util;
 
+import static org.apache.hadoop.util.RunJar.MATCH_ANY;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
+import static org.mockito.Matchers.any;
 import static org.mockito.Mockito.spy;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
 import java.io.File;
@@ -99,7 +103,7 @@ public void testUnJar() throws Exception {
 
     // Unjar everything
     RunJar.unJar(new File(TEST_ROOT_DIR, TEST_JAR_NAME),
-                 unjarDir);
+                 unjarDir, MATCH_ANY);
     assertTrue("foobar unpacked",
                new File(unjarDir, TestRunJar.FOOBAR_TXT).exists());
     assertTrue("foobaz unpacked",
@@ -177,7 +181,7 @@ public void testUnJarDoesNotLooseLastModify() throws Exception {
 
     // Unjar everything
     RunJar.unJar(new File(TEST_ROOT_DIR, TEST_JAR_NAME),
-            unjarDir);
+            unjarDir, MATCH_ANY);
 
     String failureMessage = "Last modify time was lost during unJar";
     assertEquals(failureMessage, MOCKED_NOW, new File(unjarDir, TestRunJar.FOOBAR_TXT).lastModified());
@@ -221,5 +225,34 @@ public void testClientClassLoader() throws Throwable {
     // run RunJar
     runJar.run(args);
     // it should not throw an exception
+    verify(runJar, times(1)).unJar(any(File.class), any(File.class));
+  }
+
+  @Test
+  public void testClientClassLoaderSkipUnjar() throws Throwable {
+    RunJar runJar = spy(new RunJar());
+    // enable the client classloader
+    when(runJar.useClientClassLoader()).thenReturn(true);
+    // set the system classes and blacklist the test main class and the test
+    // third class so they can be loaded by the application classloader
+    String mainCls = ClassLoaderCheckMain.class.getName();
+    String thirdCls = ClassLoaderCheckThird.class.getName();
+    String systemClasses = "-" + mainCls + "," +
+        "-" + thirdCls + "," +
+        ApplicationClassLoader.SYSTEM_CLASSES_DEFAULT;
+    when(runJar.getSystemClasses()).thenReturn(systemClasses);
+
+    // create the test jar
+    File testJar = JarFinder.makeClassLoaderTestJar(this.getClass(),
+        TEST_ROOT_DIR, TEST_JAR_2_NAME, BUFF_SIZE, mainCls, thirdCls);
+    // form the args
+    String[] args = new String[3];
+    args[0] = testJar.getAbsolutePath();
+    args[1] = mainCls;
+    when(runJar.skipUnjar()).thenReturn(true);
+    // run RunJar
+    runJar.run(args);
+    // it should not throw an exception
+    verify(runJar, times(0)).unJar(any(File.class), any(File.class));
   }
 }
\ No newline at end of file
diff --git a/hadoop-tools/hadoop-streaming/src/main/java/org/apache/hadoop/streaming/StreamJob.java b/hadoop-tools/hadoop-streaming/src/main/java/org/apache/hadoop/streaming/StreamJob.java
index 9b09729741..1fe8710f01 100644
--- a/hadoop-tools/hadoop-streaming/src/main/java/org/apache/hadoop/streaming/StreamJob.java
+++ b/hadoop-tools/hadoop-streaming/src/main/java/org/apache/hadoop/streaming/StreamJob.java
@@ -72,6 +72,8 @@
 import org.apache.hadoop.util.StringUtils;
 import org.apache.hadoop.util.Tool;
 
+import static org.apache.hadoop.util.RunJar.MATCH_ANY;
+
 /** All the client-side work happens here.
  * (Jar packaging, MapRed job submission and monitoring)
  */
@@ -1006,7 +1008,7 @@ public int submitAndMonitorJob() throws IOException {
     if (jar_ != null && isLocalHadoop()) {
       // getAbs became required when shell and subvm have different working dirs...
       File wd = new File(".").getAbsoluteFile();
-      RunJar.unJar(new File(jar_), wd);
+      RunJar.unJar(new File(jar_), wd, MATCH_ANY);
     }
 
     // if jobConf_ changes must recreate a JobClient