Index: src/__phutil_library_map__.php
===================================================================
--- src/__phutil_library_map__.php
+++ src/__phutil_library_map__.php
@@ -1055,6 +1055,7 @@
     'PasteMockMailReceiver' => 'applications/paste/mail/PasteMockMailReceiver.php',
     'PasteReplyHandler' => 'applications/paste/mail/PasteReplyHandler.php',
     'PeopleCapabilityBrowseUserDirectory' => 'applications/people/capability/PeopleCapabilityBrowseUserDirectory.php',
+    'PeopleUserLogGarbageCollector' => 'applications/people/garbagecollector/PeopleUserLogGarbageCollector.php',
     'Phabricator404Controller' => 'applications/base/controller/Phabricator404Controller.php',
     'PhabricatorAWSConfigOptions' => 'applications/config/option/PhabricatorAWSConfigOptions.php',
     'PhabricatorAccessControlTestCase' => 'applications/base/controller/__tests__/PhabricatorAccessControlTestCase.php',
@@ -3665,6 +3666,7 @@
     'PasteMockMailReceiver' => 'PhabricatorObjectMailReceiver',
     'PasteReplyHandler' => 'PhabricatorMailReplyHandler',
     'PeopleCapabilityBrowseUserDirectory' => 'PhabricatorPolicyCapability',
+    'PeopleUserLogGarbageCollector' => 'PhabricatorGarbageCollector',
     'Phabricator404Controller' => 'PhabricatorController',
     'PhabricatorAWSConfigOptions' => 'PhabricatorApplicationConfigOptions',
     'PhabricatorAccessControlTestCase' => 'PhabricatorTestCase',
Index: src/applications/people/garbagecollector/PeopleUserLogGarbageCollector.php
===================================================================
--- /dev/null
+++ src/applications/people/garbagecollector/PeopleUserLogGarbageCollector.php
@@ -0,0 +1,21 @@
+<?php
+
+final class PeopleUserLogGarbageCollector
+  extends PhabricatorGarbageCollector {
+
+  public function collectGarbage() {
+    $ttl = phutil_units('180 days in seconds');
+
+    $table = new PhabricatorUserLog();
+    $conn_w = $table->establishConnection('w');
+
+    queryfx(
+      $conn_w,
+      'DELETE FROM %T WHERE dateCreated < %d LIMIT 100',
+      $table->getTableName(),
+      time() - $ttl);
+
+    return ($conn_w->getAffectedRows() == 100);
+  }
+
+}