diff --git a/src/applications/config/controller/PhabricatorConfigVersionController.php b/src/applications/config/controller/PhabricatorConfigVersionController.php
--- a/src/applications/config/controller/PhabricatorConfigVersionController.php
+++ b/src/applications/config/controller/PhabricatorConfigVersionController.php
@@ -39,8 +39,20 @@
     $versions = $this->loadVersions($viewer);
 
     $version_property_list = id(new PHUIPropertyListView());
-    foreach ($versions as $name => $version) {
-      $version_property_list->addProperty($name, $version);
+    foreach ($versions as $name => $info) {
+      $version = $info['version'];
+
+      if ($info['branchpoint']) {
+        $display = pht(
+          '%s (branched from %s on %s)',
+          $version,
+          $info['branchpoint'],
+          $info['upstream']);
+      } else {
+        $display = $version;
+      }
+
+      $version_property_list->addProperty($name, $display);
     }
 
     $phabricator_root = dirname(phutil_get_library_root('phabricator'));
@@ -67,16 +79,109 @@
     $other_libraries = array_diff($all_libraries, $specs);
     $specs = array_merge($specs, $other_libraries);
 
-    $futures = array();
+    $log_futures = array();
+    $remote_futures = array();
+
     foreach ($specs as $lib) {
       $root = dirname(phutil_get_library_root($lib));
-      $futures[$lib] =
-        id(new ExecFuture('git log --format=%s -n 1 --', '%H %ct'))
+
+      $log_command = csprintf(
+        'git log --format=%s -n 1 --',
+        '%H %ct');
+
+      $remote_command = csprintf(
+        'git remote -v');
+
+      $log_futures[$lib] = id(new ExecFuture('%C', $log_command))
+        ->setCWD($root);
+
+      $remote_futures[$lib] = id(new ExecFuture('%C', $remote_command))
         ->setCWD($root);
     }
 
+    $all_futures = array_merge($log_futures, $remote_futures);
+
+    id(new FutureIterator($all_futures))
+      ->resolveAll();
+
+    // A repository may have a bunch of remotes, but we're only going to look
+    // for remotes we host to try to figure out where this repository branched.
+    $upstream_pattern = '(github\.com/phacility/|secure\.phabricator\.com/)';
+
+    $upstream_futures = array();
+    $lib_upstreams = array();
+    foreach ($specs as $lib) {
+      $remote_future = $remote_futures[$lib];
+
+      list($err, $stdout) = $remote_future->resolve();
+      if ($err) {
+        // If this fails for whatever reason, just move on.
+        continue;
+      }
+
+      // These look like this, with a tab separating the first two fields:
+      // remote-name     http://remote.uri/ (push)
+
+      $upstreams = array();
+
+      $remotes = phutil_split_lines($stdout, false);
+      foreach ($remotes as $remote) {
+        $remote_pattern = '/^([^\t]+)\t([^ ]+) \(([^)]+)\)\z/';
+        $matches = null;
+        if (!preg_match($remote_pattern, $remote, $matches)) {
+          continue;
+        }
+
+        // Remote URIs are either "push" or "fetch": we only care about "fetch"
+        // URIs.
+        $type = $matches[3];
+        if ($type != 'fetch') {
+          continue;
+        }
+
+        $uri = $matches[2];
+        $is_upstream = preg_match($upstream_pattern, $uri);
+        if (!$is_upstream) {
+          continue;
+        }
+
+        $name = $matches[1];
+        $upstreams[$name] = $name;
+      }
+
+      // If we have several suitable upstreams, try to pick the one named
+      // "origin", if it exists. Otherwise, just pick the first one.
+      if (isset($upstreams['origin'])) {
+        $upstream = $upstreams['origin'];
+      } else if ($upstreams) {
+        $upstream = head($upstreams);
+      } else {
+        $upstream = null;
+      }
+
+      if (!$upstream) {
+        continue;
+      }
+
+      $lib_upstreams[$lib] = $upstream;
+
+      $merge_base_command = csprintf(
+        'git merge-base HEAD %s/master --',
+        $upstream);
+
+      $root = dirname(phutil_get_library_root($lib));
+
+      $upstream_futures[$lib] = id(new ExecFuture('%C', $merge_base_command))
+        ->setCWD($root);
+    }
+
+    if ($upstream_futures) {
+      id(new FutureIterator($upstream_futures))
+        ->resolveAll();
+    }
+
     $results = array();
-    foreach ($futures as $key => $future) {
+    foreach ($log_futures as $lib => $future) {
       list($err, $stdout) = $future->resolve();
       if (!$err) {
         list($hash, $epoch) = explode(' ', $stdout);
@@ -84,7 +189,29 @@
       } else {
         $version = pht('Unknown');
       }
-      $results[$key] = $version;
+
+      $result = array(
+        'version' => $version,
+        'upstream' => null,
+        'branchpoint' => null,
+      );
+
+      $upstream_future = idx($upstream_futures, $lib);
+      if ($upstream_future) {
+        list($err, $stdout) = $upstream_future->resolve();
+        if (!$err) {
+          $branchpoint = trim($stdout);
+          if (strlen($branchpoint)) {
+            // We only list a branchpoint if it differs from HEAD.
+            if ($branchpoint != $hash) {
+              $result['upstream'] = $lib_upstreams[$lib];
+              $result['branchpoint'] = trim($stdout);
+            }
+          }
+        }
+      }
+
+      $results[$lib] = $result;
     }
 
     return $results;
diff --git a/src/docs/contributor/version.diviner b/src/docs/contributor/version.diviner
--- a/src/docs/contributor/version.diviner
+++ b/src/docs/contributor/version.diviner
@@ -49,6 +49,29 @@
 prevents you from reaching the version reporting screen.
 
 
+Running a Fork?
+===============
+
+If you've forked Phabricator and have local commits, please make sure you are
+reporting upstream commit hashes, not local commit hashes. The UI will attempt
+to figure out where you branched from, but it may not be able to in all cases.
+
+If you report local commit hashes instead of upstream commit hashes we can not
+go look up the commit hashes to figure out which changes they correspond to, so
+we can not use that information to determine out how old your install is or
+which patches you are missing.
+
+In most cases, you can find the upstream commit you've branched from like this:
+
+```
+$ git merge-base HEAD origin/master
+````
+
+Note that if you report a bug and have local commits, we will almost always ask
+you to reproduce the issue against a clean copy of Phabricator before we
+continue. You can get help faster by doing this //before// reporting an issue.
+
+
 Next Steps
 ==========