diff --git a/hadoop-common-project/hadoop-common/CHANGES.txt b/hadoop-common-project/hadoop-common/CHANGES.txt
index 8cdf3264061..fd0d92df215 100644
--- a/hadoop-common-project/hadoop-common/CHANGES.txt
+++ b/hadoop-common-project/hadoop-common/CHANGES.txt
@@ -105,6 +105,9 @@ Release 2.0.3-alpha - Unreleased
 
   BUG FIXES
 
+    HADOOP-8418. Update UGI Principal classes name for running with
+    IBM JDK on 64 bits Windows.  (Yu Gao via eyang)
+
     HADOOP-8795. BASH tab completion doesn't look in PATH, assumes path to
     executable is specified. (Sean Mackrory via atm)
 
diff --git a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/UserGroupInformation.java b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/UserGroupInformation.java
index bfce807e32c..4e3cfab9865 100644
--- a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/UserGroupInformation.java
+++ b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/UserGroupInformation.java
@@ -288,13 +288,17 @@ public class UserGroupInformation {
   
   private static String OS_LOGIN_MODULE_NAME;
   private static Class<? extends Principal> OS_PRINCIPAL_CLASS;
-  private static final boolean windows = 
-                           System.getProperty("os.name").startsWith("Windows");
+  private static final boolean windows =
+      System.getProperty("os.name").startsWith("Windows");
+  private static final boolean is64Bit =
+      System.getProperty("os.arch").contains("64");
   /* Return the OS login module class name */
   private static String getOSLoginModuleName() {
     if (System.getProperty("java.vendor").contains("IBM")) {
-      return windows ? "com.ibm.security.auth.module.NTLoginModule"
-       : "com.ibm.security.auth.module.LinuxLoginModule";
+      return windows ? (is64Bit
+          ? "com.ibm.security.auth.module.Win64LoginModule"
+          : "com.ibm.security.auth.module.NTLoginModule")
+        : "com.ibm.security.auth.module.LinuxLoginModule";
     } else {
       return windows ? "com.sun.security.auth.module.NTLoginModule"
         : "com.sun.security.auth.module.UnixLoginModule";
@@ -308,13 +312,13 @@ public class UserGroupInformation {
     try {
       if (System.getProperty("java.vendor").contains("IBM")) {
         if (windows) {
-          return (Class<? extends Principal>)
-            cl.loadClass("com.ibm.security.auth.UsernamePrincipal");
+          return (Class<? extends Principal>) (is64Bit
+            ? cl.loadClass("com.ibm.security.auth.UsernamePrincipal")
+            : cl.loadClass("com.ibm.security.auth.NTUserPrincipal"));
         } else {
-          return (Class<? extends Principal>)
-            (System.getProperty("os.arch").contains("64")
-             ? cl.loadClass("com.ibm.security.auth.UsernamePrincipal")
-             : cl.loadClass("com.ibm.security.auth.LinuxPrincipal"));
+          return (Class<? extends Principal>) (is64Bit
+            ? cl.loadClass("com.ibm.security.auth.UsernamePrincipal")
+            : cl.loadClass("com.ibm.security.auth.LinuxPrincipal"));
         }
       } else {
         return (Class<? extends Principal>) (windows