diff --git a/changelog.html b/changelog.html
index 62718805e90c0bf0c17acf8a07d6d27cabb7bb20..824da3ec755928401a81507d9894a03552ffa3d1 100644
--- a/changelog.html
+++ b/changelog.html
@@ -55,6 +55,11 @@ Upcoming changes</a>
 <!-- Record your changes in the trunk here. -->
 <div id="trunk" style="display:none"><!--=TRUNK-BEGIN=-->
 <ul class=image>
+  <li class='major rfe'>
+    <b><tt>JENKINS_HOME</tt> layout change</b>: builds are now keyed by build numbers and not timestamps.
+    See <a href="https://wiki.jenkins-ci.org/display/JENKINS/JENKINS-24380+Migration">Wiki</a> for details
+    and downgrade.
+    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-24380">issue 24380</a>)
   <li class=bug>
     Fingerprint compaction aggravated lazy-loading performance issues.
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-19392">issue 19392</a>)
@@ -123,7 +128,7 @@ Upcoming changes</a>
 <ul class=image>
   <li class=bug>
     Always use forward slashes in path separators during in ZIP archives generated by Directory Browser
-    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-22514">issue 22514</a>)  
+    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-22514">issue 22514</a>)
 </ul>
 <h3><a name=v1.590>What's new in 1.590</a> (2014/11/16)</h3>
 <ul class=image>
@@ -135,7 +140,7 @@ Upcoming changes</a>
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-25400">issue 25400</a>)
   <li class=bug>
     Fixed various real or potential resource leaks discovered by <a href="https://scan.coverity.com/projects/94/">Coverity Scan</code>
-    (<a href="https://github.com/jenkinsci/jenkins/pull/1434">pull request 1434</a>)  
+    (<a href="https://github.com/jenkinsci/jenkins/pull/1434">pull request 1434</a>)
   <li class=rfe>
     API changes: Expose <code>AbstractProject.AbstractProjectDescriptor#validateLabelExpression</code> for plugins.
     (<a href="https://github.com/jenkinsci/jenkins/pull/1456">pull request 1456</a>)
@@ -144,7 +149,7 @@ Upcoming changes</a>
     (<a href="https://github.com/jenkinsci/jenkins/pull/1458">pull request 1458</a>)
   <li class=rfe>
     API method to get non-null <code>Jenkins</code> instance with internal validation
-    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-23339">issue 23339</a>)    
+    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-23339">issue 23339</a>)
 </ul>
 <h3><a name=v1.589>What's new in 1.589</a> (2014/11/09)</h3>
 <ul class=image>
@@ -190,7 +195,7 @@ Upcoming changes</a>
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-25019">issue 25019</a>)
   <li class=bug>
     Existing <code>FileParameter</code>s should be handled as different values to avoid merging of queued builds
-    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-19017">issue 19017</a>)  
+    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-19017">issue 19017</a>)
 </ul>
 <h3><a name=v1.585>What's new in 1.585</a> (2014/10/19)</h3>
 <ul class=image>
@@ -210,22 +215,22 @@ Upcoming changes</a>
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-25065">issue 25065</a>)
   <li class=bug>
     Greater-than characters are not escaped in HTML outputs like e-mails
-    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-16184">issue 16184</a>)  
+    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-16184">issue 16184</a>)
   <li class=bug>
     Thread starvation from <code>OldDataMonitor</code>.
-    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-24763">issue 24763</a>)  
+    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-24763">issue 24763</a>)
   <li class=bug>
-    Integer overflow in quiet-down timeout calculation 
-    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-24914">issue 24914</a>)  
+    Integer overflow in quiet-down timeout calculation
+    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-24914">issue 24914</a>)
   <li class=bug>
     Don't put session IDs in URLs even when cookies are disabled.
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-22358">issue 22358</a>)
   <li class=rfe>
     Show keep build log reason in tool tips
-    (<a href="https://github.com/jenkinsci/jenkins/pull/1422">pull request 1422</a>)  
+    (<a href="https://github.com/jenkinsci/jenkins/pull/1422">pull request 1422</a>)
   <li class=bug>
     Do not disable projects, which do not support such operation (like Matrix configurations)
-    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-24340">issue 24340</a>)  
+    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-24340">issue 24340</a>)
   <li class=rfe>
     Improved the scalability of SSH slaves plugin caused by global lock in <tt>SecureRandom</tt>
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-20108">issue 20108</a>)
@@ -479,7 +484,7 @@ Upcoming changes</a>
 <ul class=image>
   <li class="rfe">
     UI redesign: Use Helvetica as default font
-    (<a href="https://github.com/jenkinsci/jenkins/pull/1315">pull 1315</a>, 
+    (<a href="https://github.com/jenkinsci/jenkins/pull/1315">pull 1315</a>,
     <a href="https://issues.jenkins-ci.org/browse/JENKINS-23840">issue 23840</a>)
   <li class="bug">
     Synchronization issue during tool installation
@@ -622,7 +627,7 @@ Upcoming changes</a>
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-20499">issue 20499</a>)
   <li class="bug">
     Fixed <code>NullPointerException</code> on plugin installations when invalid update center is set
-    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-20031">issue 20031</a>)  
+    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-20031">issue 20031</a>)
   <li class="bug">
     Use DISABLED_ANIME icon while building a disabled project
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-8358">issue 8358</a>)
@@ -635,22 +640,22 @@ Upcoming changes</a>
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-18116">issue 18116</a>)
   <li class="bug">
     Properly close input streams in <code>FileParameterValue</code>
-    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-22693">issue 22693</a>)      
+    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-22693">issue 22693</a>)
   <li class="bug">
     Incorrect failure age in the JUnit test results
-    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-18626">issue 18626</a>)  
+    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-18626">issue 18626</a>)
   <li class="bug">
     Fixed deletion links for JVM Crash error logs
-    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-22617">issue 22617</a>)  
+    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-22617">issue 22617</a>)
   <li class="rfe">
     Distinguish &quot;nodes for label offline&quot; from &quot;no nodes for label&quot;
-    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-17114">issue 17114</a>)  
+    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-17114">issue 17114</a>)
   <li class="rfe">
     Add causes to queue item tool tip
-    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-19250">issue 19250</a>)  
+    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-19250">issue 19250</a>)
   <li class="rfe">
     RPM: added JENKINS_HTTPS_KEYSTORE and JENKINS_HTTPS_KEYSTORE_PASSWORD options to Jenkins sysconfig file
-    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-11673">issue 11673</a>)  
+    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-11673">issue 11673</a>)
   <li class="bug">
     RPM: Do not install jenkins.repo file
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-22690">issue 22690</a>)
@@ -1000,7 +1005,7 @@ Upcoming changes</a>
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-19559">issue 19559</a>)
   <li class=bug>
     Fix autocompletion for items in folders.
-    (<a href="https://github.com/jenkinsci/jenkins/pull/1124">pull request 1124</a>)  
+    (<a href="https://github.com/jenkinsci/jenkins/pull/1124">pull request 1124</a>)
 </ul>
 <h3><a name=v1.552>What's new in 1.552</a> (2014/02/24)</h3>
 <ul class=image>
@@ -1307,7 +1312,7 @@ Upcoming changes</a>
     Added CLI commands that manipulate views
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-19996">issue 19996</a>)
   <li class=rfe>
-    Improved the /cli help screen. 
+    Improved the /cli help screen.
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-20023">issue 20023</a>)
   <li class=bug>
     Polling-triggered jobs get scheduled en-mass on start-up if slaves aren't online yet.
@@ -1377,7 +1382,7 @@ Upcoming changes</a>
     <a href="https://issues.jenkins-ci.org/browse/JENKINS-18879">issue 18879</a>,
     <a href="https://issues.jenkins-ci.org/browse/JENKINS-19619">issue 19619</a>)
   <li class='major rfe'>
-    Upgrade bundled iplugin versions: ssh-slaves to 1.4, ssh-credentials to 1.5.3 and 
+    Upgrade bundled iplugin versions: ssh-slaves to 1.4, ssh-credentials to 1.5.3 and
     credentials to 1.8.3
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-19945">issue 19945</a>)
   <li class='major rfe'>
@@ -1967,7 +1972,7 @@ Upcoming changes</a>
     ”My Views" links leads to 404 Not Found.
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-17317">issue 17317</a>)
   <li class=bug>
-    Quoting Issue with JDK Installer with Windows Installer. 
+    Quoting Issue with JDK Installer with Windows Installer.
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-5408">issue 5408</a>)
   <li class=bug>
     Restored compatibility in <code>ArtifactArchiver</code> signature; broken in 1.509 and could affect plugins.
@@ -2043,7 +2048,7 @@ Upcoming changes</a>
     ChangeLog should produce some output even if some (plugin) annotator fails
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-17084">issue 17084</a>)
   <li class=bug>
-    View name should not allow "..".    
+    View name should not allow "..".
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-16608">issue 16608</a>)
 </ul>
 <h3><a name=v1.508>What's new in 1.508</a> (2013/03/25)</h3>
@@ -2075,7 +2080,7 @@ Upcoming changes</a>
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-16089">issue 16089</a>)
   <li class=bug>
     Wrong build result in post build steps after failed pre build step in maven projects.
-    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-17177">issue 17177</a>)     
+    (<a href="https://issues.jenkins-ci.org/browse/JENKINS-17177">issue 17177</a>)
 </ul>
 <h3><a name=v1.506>What's new in 1.506</a> (2013/03/17)</h3>
 <ul class=image>
@@ -2264,7 +2269,7 @@ Upcoming changes</a>
   <li class=bug>
     Fixed NullPointerException when copying from existing Maven job
     (<a href="https://issues.jenkins-ci.org/browse/JENKINS-16499">issue 16499</a>)
-    
+
 </ul>
 <h3><a name=v1.500>What's new in 1.500</a> (2013/01/26)</h3>
 <ul class=image>
diff --git a/core/src/main/java/jenkins/model/RunIdMigrator.java b/core/src/main/java/jenkins/model/RunIdMigrator.java
index 61fe4c48ae4c317eb5acf2017c59b004e9129219..4097fdea0f9f763bbd9cd44959c8371b72adbb5d 100644
--- a/core/src/main/java/jenkins/model/RunIdMigrator.java
+++ b/core/src/main/java/jenkins/model/RunIdMigrator.java
@@ -24,8 +24,10 @@
 
 package jenkins.model;
 
+import hudson.Extension;
 import hudson.Util;
 import hudson.model.Job;
+import hudson.model.RootAction;
 import hudson.model.Run;
 import hudson.util.AtomicFileWriter;
 import hudson.util.StreamTaskListener;
@@ -58,6 +60,8 @@ import org.apache.commons.lang.time.FastDateFormat;
 import org.apache.tools.ant.BuildException;
 import org.kohsuke.accmod.Restricted;
 import org.kohsuke.accmod.restrictions.NoExternalUse;
+import org.kohsuke.stapler.HttpResponse;
+import org.kohsuke.stapler.StaplerProxy;
 import org.kohsuke.stapler.framework.io.WriterOutputStream;
 
 import static java.util.logging.Level.*;
@@ -158,26 +162,29 @@ public final class RunIdMigrator {
         LOGGER.log(INFO, "Migrating build records in {0}", dir);
         doMigrate(dir);
         save(dir);
-        if (jenkinsHome != null && offeredToUnmigrate.add(jenkinsHome)) {
-            StringBuilder cp = new StringBuilder();
-            for (Class<?> c : new Class<?>[] {RunIdMigrator.class, /* TODO how to calculate transitive dependencies automatically? */Charsets.class, WriterOutputStream.class, BuildException.class, FastDateFormat.class}) {
-                URL location = c.getProtectionDomain().getCodeSource().getLocation();
-                String locationS = location.toString();
-                if (location.getProtocol().equals("file")) {
-                    try {
-                        locationS = new File(location.toURI()).getAbsolutePath();
-                    } catch (URISyntaxException x) {
-                        // never mind
-                    }
-                }
-                if (cp.length() > 0) {
-                    cp.append(File.pathSeparator);
+        if (jenkinsHome != null && offeredToUnmigrate.add(jenkinsHome))
+            LOGGER.log(WARNING, "Build record migration is one-way. If you need to downgrade Jenkins, run: {0}", getUnmigrationCommandLine(jenkinsHome));
+        return true;
+    }
+
+    private static String getUnmigrationCommandLine(File jenkinsHome) {
+        StringBuilder cp = new StringBuilder();
+        for (Class<?> c : new Class<?>[] {RunIdMigrator.class, /* TODO how to calculate transitive dependencies automatically? */Charsets.class, WriterOutputStream.class, BuildException.class, FastDateFormat.class}) {
+            URL location = c.getProtectionDomain().getCodeSource().getLocation();
+            String locationS = location.toString();
+            if (location.getProtocol().equals("file")) {
+                try {
+                    locationS = new File(location.toURI()).getAbsolutePath();
+                } catch (URISyntaxException x) {
+                    // never mind
                 }
-                cp.append(locationS);
             }
-            LOGGER.log(WARNING, "Build record migration is one-way. If you need to downgrade Jenkins, run: java -classpath {0} {1} \"{2}\"", new Object[] {cp, RunIdMigrator.class.getName(), jenkinsHome});
+            if (cp.length() > 0) {
+                cp.append(File.pathSeparator);
+            }
+            cp.append(locationS);
         }
-        return true;
+        return String.format("java -classpath \"%s\" %s \"%s\"", cp, RunIdMigrator.class.getName(), jenkinsHome);
     }
 
     private static final Pattern NUMBER_ELT = Pattern.compile("(?m)^  <number>(\\d+)</number>(\r?\n)");
@@ -367,4 +374,34 @@ public final class RunIdMigrator {
         System.err.println(builds + " has been restored to its original format");
     }
 
+    /**
+     * Expose unmigration instruction to the user.
+     */
+    @Extension
+    public static class UnmigrationInstruction implements RootAction, StaplerProxy {
+        @Override
+        public String getIconFileName() {
+            return null;
+        }
+
+        @Override
+        public String getDisplayName() {
+            return null;
+        }
+
+        @Override
+        public String getUrlName() {
+            return "JENKINS-24380";
+        }
+
+        @Override
+        public Object getTarget() {
+            Jenkins.getInstance().checkPermission(Jenkins.ADMINISTER);
+            return this;
+        }
+
+        public String getCommand() {
+            return RunIdMigrator.getUnmigrationCommandLine(Jenkins.getInstance().getRootDir());
+        }
+    }
 }
diff --git a/core/src/main/resources/jenkins/model/RunIdMigrator/UnmigrationInstruction/index.jelly b/core/src/main/resources/jenkins/model/RunIdMigrator/UnmigrationInstruction/index.jelly
new file mode 100644
index 0000000000000000000000000000000000000000..6385169b5dee33b39c778ca14c1769234d5040e9
--- /dev/null
+++ b/core/src/main/resources/jenkins/model/RunIdMigrator/UnmigrationInstruction/index.jelly
@@ -0,0 +1,47 @@
+<!--
+The MIT License
+
+Copyright (c) 2014, CloudBees, Inc.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+-->
+
+<?jelly escape-by-default='true'?>
+<j:jelly xmlns:j="jelly:core" xmlns:st="jelly:stapler" xmlns:d="jelly:define" xmlns:l="/lib/layout" xmlns:t="/lib/hudson" xmlns:f="/lib/form" xmlns:i="jelly:fmt">
+  <l:layout title="Jenkins">
+    <l:header />
+    <l:main-panel>
+      <p>
+        To reverse the effect of <a href="http://jenkins-ci.org/issue/24380">JENKINS-24380</a> fix, run the following command
+        on the server. See <a href="https://wiki.jenkins-ci.org/display/JENKINS/JENKINS-24380+Migration">Wiki page</a>
+        for more details:
+      </p>
+      <table style="width:100%">
+        <tr>
+          <td style="line-height:2em; width:80%">
+            <input type="text" value="${it.command}" style="width:100%"/>
+          </td>
+          <td style="line-height:2em">
+            <l:copyButton message="${%Copied}" text="${it.command}"/>
+          </td>
+        </tr>
+      </table>
+    </l:main-panel>
+  </l:layout>
+</j:jelly>