diff --git a/resources/sql/autopatches/20190117.authmessage.01.message.sql b/resources/sql/autopatches/20190117.authmessage.01.message.sql
new file mode 100644
--- /dev/null
+++ b/resources/sql/autopatches/20190117.authmessage.01.message.sql
@@ -0,0 +1,8 @@
+CREATE TABLE {$NAMESPACE}_auth.auth_message (
+  id INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
+  phid VARBINARY(64) NOT NULL,
+  messageKey VARCHAR(64) NOT NULL COLLATE {$COLLATE_TEXT},
+  messageText LONGTEXT NOT NULL COLLATE {$COLLATE_TEXT},
+  dateCreated INT UNSIGNED NOT NULL,
+  dateModified INT UNSIGNED NOT NULL
+) ENGINE=InnoDB, COLLATE {$COLLATE_TEXT};
diff --git a/resources/sql/autopatches/20190117.authmessage.02.xaction.sql b/resources/sql/autopatches/20190117.authmessage.02.xaction.sql
new file mode 100644
--- /dev/null
+++ b/resources/sql/autopatches/20190117.authmessage.02.xaction.sql
@@ -0,0 +1,19 @@
+CREATE TABLE {$NAMESPACE}_auth.auth_messagetransaction (
+  id INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
+  phid VARBINARY(64) NOT NULL,
+  authorPHID VARBINARY(64) NOT NULL,
+  objectPHID VARBINARY(64) NOT NULL,
+  viewPolicy VARBINARY(64) NOT NULL,
+  editPolicy VARBINARY(64) NOT NULL,
+  commentPHID VARBINARY(64) DEFAULT NULL,
+  commentVersion INT UNSIGNED NOT NULL,
+  transactionType VARCHAR(32) NOT NULL,
+  oldValue LONGTEXT NOT NULL,
+  newValue LONGTEXT NOT NULL,
+  contentSource LONGTEXT NOT NULL,
+  metadata LONGTEXT NOT NULL,
+  dateCreated INT UNSIGNED NOT NULL,
+  dateModified INT UNSIGNED NOT NULL,
+  UNIQUE KEY `key_phid` (`phid`),
+  KEY `key_object` (`objectPHID`)
+) ENGINE=InnoDB DEFAULT CHARSET={$CHARSET} COLLATE {$COLLATE_TEXT};
diff --git a/src/__phutil_library_map__.php b/src/__phutil_library_map__.php
--- a/src/__phutil_library_map__.php
+++ b/src/__phutil_library_map__.php
@@ -2246,6 +2246,7 @@
     'PhabricatorAuthListController' => 'applications/auth/controller/config/PhabricatorAuthListController.php',
     'PhabricatorAuthLoginController' => 'applications/auth/controller/PhabricatorAuthLoginController.php',
     'PhabricatorAuthLoginHandler' => 'applications/auth/handler/PhabricatorAuthLoginHandler.php',
+    'PhabricatorAuthLoginMessageType' => 'applications/auth/message/PhabricatorAuthLoginMessageType.php',
     'PhabricatorAuthLogoutConduitAPIMethod' => 'applications/auth/conduit/PhabricatorAuthLogoutConduitAPIMethod.php',
     'PhabricatorAuthMFAEditEngineExtension' => 'applications/auth/engineextension/PhabricatorAuthMFAEditEngineExtension.php',
     'PhabricatorAuthMainMenuBarExtension' => 'applications/auth/extension/PhabricatorAuthMainMenuBarExtension.php',
@@ -2261,6 +2262,20 @@
     'PhabricatorAuthManagementUntrustOAuthClientWorkflow' => 'applications/auth/management/PhabricatorAuthManagementUntrustOAuthClientWorkflow.php',
     'PhabricatorAuthManagementVerifyWorkflow' => 'applications/auth/management/PhabricatorAuthManagementVerifyWorkflow.php',
     'PhabricatorAuthManagementWorkflow' => 'applications/auth/management/PhabricatorAuthManagementWorkflow.php',
+    'PhabricatorAuthMessage' => 'applications/auth/storage/PhabricatorAuthMessage.php',
+    'PhabricatorAuthMessageController' => 'applications/auth/controller/message/PhabricatorAuthMessageController.php',
+    'PhabricatorAuthMessageEditController' => 'applications/auth/controller/message/PhabricatorAuthMessageEditController.php',
+    'PhabricatorAuthMessageEditEngine' => 'applications/auth/editor/PhabricatorAuthMessageEditEngine.php',
+    'PhabricatorAuthMessageEditor' => 'applications/auth/editor/PhabricatorAuthMessageEditor.php',
+    'PhabricatorAuthMessageListController' => 'applications/auth/controller/message/PhabricatorAuthMessageListController.php',
+    'PhabricatorAuthMessagePHIDType' => 'applications/auth/phid/PhabricatorAuthMessagePHIDType.php',
+    'PhabricatorAuthMessageQuery' => 'applications/auth/query/PhabricatorAuthMessageQuery.php',
+    'PhabricatorAuthMessageTextTransaction' => 'applications/auth/xaction/PhabricatorAuthMessageTextTransaction.php',
+    'PhabricatorAuthMessageTransaction' => 'applications/auth/storage/PhabricatorAuthMessageTransaction.php',
+    'PhabricatorAuthMessageTransactionQuery' => 'applications/auth/query/PhabricatorAuthMessageTransactionQuery.php',
+    'PhabricatorAuthMessageTransactionType' => 'applications/auth/xaction/PhabricatorAuthMessageTransactionType.php',
+    'PhabricatorAuthMessageType' => 'applications/auth/message/PhabricatorAuthMessageType.php',
+    'PhabricatorAuthMessageViewController' => 'applications/auth/controller/message/PhabricatorAuthMessageViewController.php',
     'PhabricatorAuthNeedsApprovalController' => 'applications/auth/controller/PhabricatorAuthNeedsApprovalController.php',
     'PhabricatorAuthNeedsMultiFactorController' => 'applications/auth/controller/PhabricatorAuthNeedsMultiFactorController.php',
     'PhabricatorAuthNewController' => 'applications/auth/controller/config/PhabricatorAuthNewController.php',
@@ -2337,6 +2352,7 @@
     'PhabricatorAuthTryFactorAction' => 'applications/auth/action/PhabricatorAuthTryFactorAction.php',
     'PhabricatorAuthUnlinkController' => 'applications/auth/controller/PhabricatorAuthUnlinkController.php',
     'PhabricatorAuthValidateController' => 'applications/auth/controller/PhabricatorAuthValidateController.php',
+    'PhabricatorAuthWelcomeMailMessageType' => 'applications/auth/message/PhabricatorAuthWelcomeMailMessageType.php',
     'PhabricatorAuthenticationConfigOptions' => 'applications/config/option/PhabricatorAuthenticationConfigOptions.php',
     'PhabricatorAutoEventListener' => 'infrastructure/events/PhabricatorAutoEventListener.php',
     'PhabricatorBadgesApplication' => 'applications/badges/application/PhabricatorBadgesApplication.php',
@@ -7920,6 +7936,7 @@
     'PhabricatorAuthListController' => 'PhabricatorAuthProviderConfigController',
     'PhabricatorAuthLoginController' => 'PhabricatorAuthController',
     'PhabricatorAuthLoginHandler' => 'Phobject',
+    'PhabricatorAuthLoginMessageType' => 'PhabricatorAuthMessageType',
     'PhabricatorAuthLogoutConduitAPIMethod' => 'PhabricatorAuthConduitAPIMethod',
     'PhabricatorAuthMFAEditEngineExtension' => 'PhabricatorEditEngineExtension',
     'PhabricatorAuthMainMenuBarExtension' => 'PhabricatorMainMenuBarExtension',
@@ -7935,6 +7952,25 @@
     'PhabricatorAuthManagementUntrustOAuthClientWorkflow' => 'PhabricatorAuthManagementWorkflow',
     'PhabricatorAuthManagementVerifyWorkflow' => 'PhabricatorAuthManagementWorkflow',
     'PhabricatorAuthManagementWorkflow' => 'PhabricatorManagementWorkflow',
+    'PhabricatorAuthMessage' => array(
+      'PhabricatorAuthDAO',
+      'PhabricatorApplicationTransactionInterface',
+      'PhabricatorPolicyInterface',
+      'PhabricatorDestructibleInterface',
+    ),
+    'PhabricatorAuthMessageController' => 'PhabricatorAuthProviderController',
+    'PhabricatorAuthMessageEditController' => 'PhabricatorAuthMessageController',
+    'PhabricatorAuthMessageEditEngine' => 'PhabricatorEditEngine',
+    'PhabricatorAuthMessageEditor' => 'PhabricatorApplicationTransactionEditor',
+    'PhabricatorAuthMessageListController' => 'PhabricatorAuthProviderController',
+    'PhabricatorAuthMessagePHIDType' => 'PhabricatorPHIDType',
+    'PhabricatorAuthMessageQuery' => 'PhabricatorCursorPagedPolicyAwareQuery',
+    'PhabricatorAuthMessageTextTransaction' => 'PhabricatorAuthMessageTransactionType',
+    'PhabricatorAuthMessageTransaction' => 'PhabricatorModularTransaction',
+    'PhabricatorAuthMessageTransactionQuery' => 'PhabricatorApplicationTransactionQuery',
+    'PhabricatorAuthMessageTransactionType' => 'PhabricatorModularTransactionType',
+    'PhabricatorAuthMessageType' => 'Phobject',
+    'PhabricatorAuthMessageViewController' => 'PhabricatorAuthMessageController',
     'PhabricatorAuthNeedsApprovalController' => 'PhabricatorAuthController',
     'PhabricatorAuthNeedsMultiFactorController' => 'PhabricatorAuthController',
     'PhabricatorAuthNewController' => 'PhabricatorAuthProviderConfigController',
@@ -8030,6 +8066,7 @@
     'PhabricatorAuthTryFactorAction' => 'PhabricatorSystemAction',
     'PhabricatorAuthUnlinkController' => 'PhabricatorAuthController',
     'PhabricatorAuthValidateController' => 'PhabricatorAuthController',
+    'PhabricatorAuthWelcomeMailMessageType' => 'PhabricatorAuthMessageType',
     'PhabricatorAuthenticationConfigOptions' => 'PhabricatorApplicationConfigOptions',
     'PhabricatorAutoEventListener' => 'PhabricatorEventListener',
     'PhabricatorBadgesApplication' => 'PhabricatorApplication',
diff --git a/src/applications/auth/application/PhabricatorAuthApplication.php b/src/applications/auth/application/PhabricatorAuthApplication.php
--- a/src/applications/auth/application/PhabricatorAuthApplication.php
+++ b/src/applications/auth/application/PhabricatorAuthApplication.php
@@ -94,6 +94,16 @@
           '(?P<id>[1-9]\d*)/' =>
             'PhabricatorAuthFactorProviderViewController',
         ),
+
+        'message/' => array(
+          $this->getQueryRoutePattern() =>
+            'PhabricatorAuthMessageListController',
+          $this->getEditRoutePattern('edit/') =>
+            'PhabricatorAuthMessageEditController',
+          '(?P<id>[1-9]\d*)/' =>
+            'PhabricatorAuthMessageViewController',
+        ),
+
       ),
 
       '/oauth/(?P<provider>\w+)/login/'
diff --git a/src/applications/auth/controller/config/PhabricatorAuthProviderController.php b/src/applications/auth/controller/config/PhabricatorAuthProviderController.php
--- a/src/applications/auth/controller/config/PhabricatorAuthProviderController.php
+++ b/src/applications/auth/controller/config/PhabricatorAuthProviderController.php
@@ -31,6 +31,20 @@
         ->setHref($this->getApplicationURI('mfa/'))
         ->setIcon('fa-mobile'));
 
+    $nav->addMenuItem(
+      id(new PHUIListItemView())
+        ->setName(pht('Onboarding'))
+        ->setType(PHUIListItemView::TYPE_LABEL));
+
+    $nav->addMenuItem(
+      id(new PHUIListItemView())
+        ->setKey('message')
+        ->setName(pht('Customize Messages'))
+        ->setType(PHUIListItemView::TYPE_LINK)
+        ->setHref($this->getApplicationURI('message/'))
+        ->setIcon('fa-commenting-o'));
+
+
     $nav->selectFilter(null);
 
     return $nav;
diff --git a/src/applications/auth/controller/message/PhabricatorAuthMessageController.php b/src/applications/auth/controller/message/PhabricatorAuthMessageController.php
new file mode 100644
--- /dev/null
+++ b/src/applications/auth/controller/message/PhabricatorAuthMessageController.php
@@ -0,0 +1,11 @@
+<?php
+
+abstract class PhabricatorAuthMessageController
+  extends PhabricatorAuthProviderController {
+
+  protected function buildApplicationCrumbs() {
+    return parent::buildApplicationCrumbs()
+      ->addTextCrumb(pht('Messages'), $this->getApplicationURI('message/'));
+  }
+
+}
diff --git a/src/applications/auth/controller/message/PhabricatorAuthMessageEditController.php b/src/applications/auth/controller/message/PhabricatorAuthMessageEditController.php
new file mode 100644
--- /dev/null
+++ b/src/applications/auth/controller/message/PhabricatorAuthMessageEditController.php
@@ -0,0 +1,31 @@
+<?php
+
+final class PhabricatorAuthMessageEditController
+  extends PhabricatorAuthMessageController {
+
+  public function handleRequest(AphrontRequest $request) {
+    $this->requireApplicationCapability(
+      AuthManageProvidersCapability::CAPABILITY);
+
+    $engine = id(new PhabricatorAuthMessageEditEngine())
+      ->setController($this);
+
+    $id = $request->getURIData('id');
+    if (!$id) {
+      $message_key = $request->getStr('messageKey');
+
+      $message_types = PhabricatorAuthMessageType::getAllMessageTypes();
+      $message_type = idx($message_types, $message_key);
+      if (!$message_type) {
+        return new Aphront404Response();
+      }
+
+      $engine
+        ->addContextParameter('messageKey', $message_key)
+        ->setMessageType($message_type);
+    }
+
+    return $engine->buildResponse();
+  }
+
+}
diff --git a/src/applications/auth/controller/message/PhabricatorAuthMessageListController.php b/src/applications/auth/controller/message/PhabricatorAuthMessageListController.php
new file mode 100644
--- /dev/null
+++ b/src/applications/auth/controller/message/PhabricatorAuthMessageListController.php
@@ -0,0 +1,77 @@
+<?php
+
+final class PhabricatorAuthMessageListController
+  extends PhabricatorAuthProviderController {
+
+  public function handleRequest(AphrontRequest $request) {
+    $viewer = $this->getViewer();
+
+    $can_manage = $this->hasApplicationCapability(
+      AuthManageProvidersCapability::CAPABILITY);
+
+    $types = PhabricatorAuthMessageType::getAllMessageTypes();
+
+    $messages = id(new PhabricatorAuthMessageQuery())
+      ->setViewer($viewer)
+      ->execute();
+    $messages = mpull($messages, null, 'getMessageKey');
+
+    $list = new PHUIObjectItemListView();
+    foreach ($types as $type) {
+      $message = idx($messages, $type->getMessageTypeKey());
+      if ($message) {
+        $href = $message->getURI();
+        $name = $message->getMessageTypeDisplayName();
+      } else {
+        $href = '/auth/message/edit/?messageKey='.$type->getMessageTypeKey();
+        $name = $type->getDisplayName();
+      }
+
+      $item = id(new PHUIObjectItemView())
+        ->setHeader($name)
+        ->setHref($href)
+        ->addAttribute($type->getShortDescription());
+
+      if ($message) {
+        $item->addIcon('fa-circle', pht('Customized'));
+      } else {
+        $item->addIcon('fa-circle-o grey', pht('Default'));
+      }
+
+      $list->addItem($item);
+    }
+
+    $crumbs = $this->buildApplicationCrumbs()
+      ->addTextCrumb(pht('Messages'))
+      ->setBorder(true);
+
+    $list->setFlush(true);
+    $list = id(new PHUIObjectBoxView())
+      ->setHeaderText(pht('Auth Messages'))
+      ->setBackground(PHUIObjectBoxView::BLUE_PROPERTY)
+      ->appendChild($list);
+
+    $title = pht('Auth Messages');
+    $header = id(new PHUIHeaderView())
+      ->setHeader($title)
+      ->setHeaderIcon('fa-commenting-o');
+
+    $view = id(new PHUITwoColumnView())
+      ->setHeader($header)
+      ->setFooter(
+        array(
+          $list,
+        ));
+
+    $nav = $this->newNavigation()
+      ->setCrumbs($crumbs)
+      ->appendChild($view);
+
+    $nav->selectFilter('message');
+
+    return $this->newPage()
+      ->setTitle($title)
+      ->appendChild($nav);
+  }
+
+}
diff --git a/src/applications/auth/controller/message/PhabricatorAuthMessageViewController.php b/src/applications/auth/controller/message/PhabricatorAuthMessageViewController.php
new file mode 100644
--- /dev/null
+++ b/src/applications/auth/controller/message/PhabricatorAuthMessageViewController.php
@@ -0,0 +1,104 @@
+<?php
+
+final class PhabricatorAuthMessageViewController
+  extends PhabricatorAuthMessageController {
+
+  public function handleRequest(AphrontRequest $request) {
+    $viewer = $this->getViewer();
+
+    $this->requireApplicationCapability(
+      AuthManageProvidersCapability::CAPABILITY);
+
+    $message = id(new PhabricatorAuthMessageQuery())
+      ->setViewer($viewer)
+      ->withIDs(array($request->getURIData('id')))
+      ->executeOne();
+    if (!$message) {
+      return new Aphront404Response();
+    }
+
+    $crumbs = $this->buildApplicationCrumbs()
+      ->addTextCrumb($message->getObjectName())
+      ->setBorder(true);
+
+    $header = $this->buildHeaderView($message);
+    $properties = $this->buildPropertiesView($message);
+    $curtain = $this->buildCurtain($message);
+
+    $timeline = $this->buildTransactionTimeline(
+      $message,
+      new PhabricatorAuthMessageTransactionQuery());
+    $timeline->setShouldTerminate(true);
+
+    $view = id(new PHUITwoColumnView())
+      ->setHeader($header)
+      ->setCurtain($curtain)
+      ->setMainColumn(
+        array(
+          $timeline,
+        ))
+      ->addPropertySection(pht('Details'), $properties);
+
+    return $this->newPage()
+      ->setTitle($message->getMessageTypeDisplayName())
+      ->setCrumbs($crumbs)
+      ->setPageObjectPHIDs(
+        array(
+          $message->getPHID(),
+        ))
+      ->appendChild($view);
+  }
+
+  private function buildHeaderView(PhabricatorAuthMessage $message) {
+    $viewer = $this->getViewer();
+
+    $view = id(new PHUIHeaderView())
+      ->setViewer($viewer)
+      ->setHeader($message->getMessageTypeDisplayName());
+
+    return $view;
+  }
+
+  private function buildPropertiesView(PhabricatorAuthMessage $message) {
+    $viewer = $this->getViewer();
+
+    $view = id(new PHUIPropertyListView())
+      ->setViewer($viewer);
+
+    $view->addProperty(
+      pht('Description'),
+      $message->getMessageType()->getShortDescription());
+
+    $view->addSectionHeader(
+      pht('Message Preview'),
+      PHUIPropertyListView::ICON_SUMMARY);
+
+    $view->addTextContent(
+      new PHUIRemarkupView($viewer, $message->getMessageText()));
+
+    return $view;
+  }
+
+  private function buildCurtain(PhabricatorAuthMessage $message) {
+    $viewer = $this->getViewer();
+    $id = $message->getID();
+
+    $can_edit = PhabricatorPolicyFilter::hasCapability(
+      $viewer,
+      $message,
+      PhabricatorPolicyCapability::CAN_EDIT);
+
+    $curtain = $this->newCurtainView($message);
+
+    $curtain->addAction(
+      id(new PhabricatorActionView())
+        ->setName(pht('Edit Message'))
+        ->setIcon('fa-pencil')
+        ->setHref($this->getApplicationURI("message/edit/{$id}/"))
+        ->setDisabled(!$can_edit)
+        ->setWorkflow(!$can_edit));
+
+    return $curtain;
+  }
+
+}
diff --git a/src/applications/auth/controller/mfa/PhabricatorAuthFactorProviderEditController.php b/src/applications/auth/controller/mfa/PhabricatorAuthFactorProviderEditController.php
--- a/src/applications/auth/controller/mfa/PhabricatorAuthFactorProviderEditController.php
+++ b/src/applications/auth/controller/mfa/PhabricatorAuthFactorProviderEditController.php
@@ -23,7 +23,7 @@
       $engine
         ->addContextParameter('providerFactorKey', $factor_key)
         ->setProviderFactor($factor);
-      }
+    }
 
     return $engine->buildResponse();
   }
diff --git a/src/applications/auth/editor/PhabricatorAuthMessageEditEngine.php b/src/applications/auth/editor/PhabricatorAuthMessageEditEngine.php
new file mode 100644
--- /dev/null
+++ b/src/applications/auth/editor/PhabricatorAuthMessageEditEngine.php
@@ -0,0 +1,108 @@
+<?php
+
+final class PhabricatorAuthMessageEditEngine
+  extends PhabricatorEditEngine {
+
+  private $messageType;
+
+  const ENGINECONST = 'auth.message';
+
+  public function isEngineConfigurable() {
+    return false;
+  }
+
+  public function getEngineName() {
+    return pht('Auth Messages');
+  }
+
+  public function getSummaryHeader() {
+    return pht('Edit Auth Messages');
+  }
+
+  public function getSummaryText() {
+    return pht('This engine is used to edit authentication messages.');
+  }
+
+  public function getEngineApplicationClass() {
+    return 'PhabricatorAuthApplication';
+  }
+
+  public function setMessageType(PhabricatorAuthMessageType $type) {
+    $this->messageType = $type;
+    return $this;
+  }
+
+  public function getMessageType() {
+    return $this->messageType;
+  }
+
+  protected function newEditableObject() {
+    $type = $this->getMessageType();
+
+    if ($type) {
+      $message = PhabricatorAuthMessage::initializeNewMessage($type);
+    } else {
+      $message = new PhabricatorAuthMessage();
+    }
+
+    return $message;
+  }
+
+  protected function newObjectQuery() {
+    return new PhabricatorAuthMessageQuery();
+  }
+
+  protected function getObjectCreateTitleText($object) {
+    return pht('Create Auth Message');
+  }
+
+  protected function getObjectCreateButtonText($object) {
+    return pht('Create Auth Message');
+  }
+
+  protected function getObjectEditTitleText($object) {
+    return pht('Edit Auth Message');
+  }
+
+  protected function getObjectEditShortText($object) {
+    return $object->getObjectName();
+  }
+
+  protected function getObjectCreateShortText() {
+    return pht('Create Auth Message');
+  }
+
+  protected function getObjectName() {
+    return pht('Auth Message');
+  }
+
+  protected function getEditorURI() {
+    return '/auth/message/edit/';
+  }
+
+  protected function getObjectCreateCancelURI($object) {
+    return '/auth/message/';
+  }
+
+  protected function getObjectViewURI($object) {
+    return $object->getURI();
+  }
+
+  protected function getCreateNewObjectPolicy() {
+    return $this->getApplication()->getPolicy(
+      AuthManageProvidersCapability::CAPABILITY);
+  }
+
+  protected function buildCustomEditFields($object) {
+    return array(
+      id(new PhabricatorRemarkupEditField())
+        ->setKey('messageText')
+        ->setTransactionType(
+          PhabricatorAuthMessageTextTransaction::TRANSACTIONTYPE)
+        ->setLabel(pht('Message Text'))
+        ->setDescription(pht('Custom text for the message.'))
+        ->setValue($object->getMessageText()),
+    );
+  }
+
+}
diff --git a/src/applications/auth/editor/PhabricatorAuthMessageEditor.php b/src/applications/auth/editor/PhabricatorAuthMessageEditor.php
new file mode 100644
--- /dev/null
+++ b/src/applications/auth/editor/PhabricatorAuthMessageEditor.php
@@ -0,0 +1,22 @@
+<?php
+
+final class PhabricatorAuthMessageEditor
+  extends PhabricatorApplicationTransactionEditor {
+
+  public function getEditorApplicationClass() {
+    return 'PhabricatorAuthApplication';
+  }
+
+  public function getEditorObjectsDescription() {
+    return pht('Auth Messages');
+  }
+
+  public function getCreateObjectTitle($author, $object) {
+    return pht('%s created this message.', $author);
+  }
+
+  public function getCreateObjectTitleForFeed($author, $object) {
+    return pht('%s created %s.', $author, $object);
+  }
+
+}
diff --git a/src/applications/auth/message/PhabricatorAuthLoginMessageType.php b/src/applications/auth/message/PhabricatorAuthLoginMessageType.php
new file mode 100644
--- /dev/null
+++ b/src/applications/auth/message/PhabricatorAuthLoginMessageType.php
@@ -0,0 +1,18 @@
+<?php
+
+final class PhabricatorAuthLoginMessageType
+  extends PhabricatorAuthMessageType {
+
+  const MESSAGEKEY = 'auth.login';
+
+  public function getDisplayName() {
+    return pht('Login Screen Instructions');
+  }
+
+  public function getShortDescription() {
+    return pht(
+      'Guidance shown on the main login screen before users log in or '.
+      'register.');
+  }
+
+}
diff --git a/src/applications/auth/message/PhabricatorAuthMessageType.php b/src/applications/auth/message/PhabricatorAuthMessageType.php
new file mode 100644
--- /dev/null
+++ b/src/applications/auth/message/PhabricatorAuthMessageType.php
@@ -0,0 +1,32 @@
+<?php
+
+abstract class PhabricatorAuthMessageType
+  extends Phobject {
+
+  final public function getMessageTypeKey() {
+    return $this->getPhobjectClassConstant('MESSAGEKEY', 64);
+  }
+
+  final public static function getAllMessageTypes() {
+    return id(new PhutilClassMapQuery())
+      ->setAncestorClass(__CLASS__)
+      ->setUniqueMethod('getMessageTypeKey')
+      ->execute();
+  }
+
+  final public static function newFromKey($key) {
+    $types = self::getAllMessageTypes();
+
+    if (empty($types[$key])) {
+      throw new Exception(
+        pht(
+          'No message type exists with key "%s".',
+          $key));
+    }
+
+    return clone $types[$key];
+  }
+
+  abstract public function getDisplayName();
+
+}
diff --git a/src/applications/auth/message/PhabricatorAuthWelcomeMailMessageType.php b/src/applications/auth/message/PhabricatorAuthWelcomeMailMessageType.php
new file mode 100644
--- /dev/null
+++ b/src/applications/auth/message/PhabricatorAuthWelcomeMailMessageType.php
@@ -0,0 +1,18 @@
+<?php
+
+final class PhabricatorAuthWelcomeMailMessageType
+  extends PhabricatorAuthMessageType {
+
+  const MESSAGEKEY = 'mail.welcome';
+
+  public function getDisplayName() {
+    return pht('Welcome Email Body');
+  }
+
+  public function getShortDescription() {
+    return pht(
+      'Custom instructions included in "Welcome" mail when an '.
+      'administrator creates a user account.');
+  }
+
+}
diff --git a/src/applications/auth/phid/PhabricatorAuthMessagePHIDType.php b/src/applications/auth/phid/PhabricatorAuthMessagePHIDType.php
new file mode 100644
--- /dev/null
+++ b/src/applications/auth/phid/PhabricatorAuthMessagePHIDType.php
@@ -0,0 +1,32 @@
+<?php
+
+final class PhabricatorAuthMessagePHIDType extends PhabricatorPHIDType {
+
+  const TYPECONST = 'AMSG';
+
+  public function getTypeName() {
+    return pht('Auth Message');
+  }
+
+  public function newObject() {
+    return new PhabricatorAuthMessage();
+  }
+
+  public function getPHIDTypeApplicationClass() {
+    return 'PhabricatorAuthApplication';
+  }
+
+  protected function buildQueryForObjects(
+    PhabricatorObjectQuery $query,
+    array $phids) {
+    return new PhabricatorAuthMessageQuery();
+  }
+
+  public function loadHandles(
+    PhabricatorHandleQuery $query,
+    array $handles,
+    array $objects) {
+    return;
+  }
+
+}
diff --git a/src/applications/auth/query/PhabricatorAuthMessageQuery.php b/src/applications/auth/query/PhabricatorAuthMessageQuery.php
new file mode 100644
--- /dev/null
+++ b/src/applications/auth/query/PhabricatorAuthMessageQuery.php
@@ -0,0 +1,83 @@
+<?php
+
+final class PhabricatorAuthMessageQuery
+  extends PhabricatorCursorPagedPolicyAwareQuery {
+
+  private $ids;
+  private $phids;
+  private $messageKeys;
+
+  public function withIDs(array $ids) {
+    $this->ids = $ids;
+    return $this;
+  }
+
+  public function withPHIDs(array $phids) {
+    $this->phids = $phids;
+    return $this;
+  }
+
+  public function withMessageKeys(array $keys) {
+    $this->messageKeys = $keys;
+    return $this;
+  }
+
+  public function newResultObject() {
+    return new PhabricatorAuthMessage();
+  }
+
+  protected function loadPage() {
+    return $this->loadStandardPage($this->newResultObject());
+  }
+
+  protected function buildWhereClauseParts(AphrontDatabaseConnection $conn) {
+    $where = parent::buildWhereClauseParts($conn);
+
+    if ($this->ids !== null) {
+      $where[] = qsprintf(
+        $conn,
+        'id IN (%Ld)',
+        $this->ids);
+    }
+
+    if ($this->phids !== null) {
+      $where[] = qsprintf(
+        $conn,
+        'phid IN (%Ls)',
+        $this->phids);
+    }
+
+    if ($this->messageKeys !== null) {
+      $where[] = qsprintf(
+        $conn,
+        'messageKey IN (%Ls)',
+        $this->messageKeys);
+    }
+
+    return $where;
+  }
+
+  protected function willFilterPage(array $messages) {
+    $message_types = PhabricatorAuthMessageType::getAllMessageTypes();
+
+    foreach ($messages as $key => $message) {
+      $message_key = $message->getMessageKey();
+
+      $message_type = idx($message_types, $message_key);
+      if (!$message_type) {
+        unset($messages[$key]);
+        $this->didRejectResult($message);
+        continue;
+      }
+
+      $message->attachMessageType($message_type);
+    }
+
+    return $messages;
+  }
+
+  public function getQueryApplicationClass() {
+    return 'PhabricatorAuthApplication';
+  }
+
+}
diff --git a/src/applications/auth/query/PhabricatorAuthMessageTransactionQuery.php b/src/applications/auth/query/PhabricatorAuthMessageTransactionQuery.php
new file mode 100644
--- /dev/null
+++ b/src/applications/auth/query/PhabricatorAuthMessageTransactionQuery.php
@@ -0,0 +1,10 @@
+<?php
+
+final class PhabricatorAuthMessageTransactionQuery
+  extends PhabricatorApplicationTransactionQuery {
+
+  public function getTemplateApplicationTransaction() {
+    return new PhabricatorAuthMessageTransaction();
+  }
+
+}
diff --git a/src/applications/auth/storage/PhabricatorAuthMessage.php b/src/applications/auth/storage/PhabricatorAuthMessage.php
new file mode 100644
--- /dev/null
+++ b/src/applications/auth/storage/PhabricatorAuthMessage.php
@@ -0,0 +1,116 @@
+<?php
+
+final class PhabricatorAuthMessage
+  extends PhabricatorAuthDAO
+  implements
+    PhabricatorApplicationTransactionInterface,
+    PhabricatorPolicyInterface,
+    PhabricatorDestructibleInterface {
+
+  protected $messageKey;
+  protected $messageText;
+
+  private $messageType = self::ATTACHABLE;
+
+  public static function initializeNewMessage(
+    PhabricatorAuthMessageType $type) {
+
+    return id(new self())
+      ->setMessageKey($type->getMessageTypeKey())
+      ->attachMessageType($type);
+  }
+
+  protected function getConfiguration() {
+    return array(
+      self::CONFIG_AUX_PHID => true,
+      self::CONFIG_COLUMN_SCHEMA => array(
+        'messageKey' => 'text64',
+        'messageText' => 'text',
+      ),
+      self::CONFIG_KEY_SCHEMA => array(
+        'key_type' => array(
+          'columns' => array('messageKey'),
+          'unique' => true,
+        ),
+      ),
+    ) + parent::getConfiguration();
+  }
+
+  public function getPHIDType() {
+    return PhabricatorAuthMessagePHIDType::TYPECONST;
+  }
+
+  public function getObjectName() {
+    return pht('Auth Message %d', $this->getID());
+  }
+
+  public function getURI() {
+    return urisprintf('/auth/message/%s', $this->getID());
+  }
+
+  public function attachMessageType(PhabricatorAuthMessageType $type) {
+    $this->messageType = $type;
+    return $this;
+  }
+
+  public function getMessageType() {
+    return $this->assertAttached($this->messageType);
+  }
+
+  public function getMessageTypeDisplayName() {
+    return $this->getMessageType()->getDisplayName();
+  }
+
+
+/* -(  PhabricatorPolicyInterface  )----------------------------------------- */
+
+
+  public function getCapabilities() {
+    return array(
+      PhabricatorPolicyCapability::CAN_VIEW,
+      PhabricatorPolicyCapability::CAN_EDIT,
+    );
+  }
+
+  public function getPolicy($capability) {
+    switch ($capability) {
+      case PhabricatorPolicyCapability::CAN_VIEW:
+        return PhabricatorPolicies::getMostOpenPolicy();
+      default:
+        return false;
+    }
+  }
+
+  public function hasAutomaticCapability($capability, PhabricatorUser $viewer) {
+    switch ($capability) {
+      case PhabricatorPolicyCapability::CAN_VIEW:
+        // Even if an install doesn't allow public users, you can still view
+        // auth messages: otherwise, we can't do things like show you
+        // guidance on the login screen.
+        return true;
+      default:
+        return false;
+    }
+  }
+
+/* -(  PhabricatorApplicationTransactionInterface  )------------------------- */
+
+
+  public function getApplicationTransactionEditor() {
+    return new PhabricatorAuthMessageEditor();
+  }
+
+  public function getApplicationTransactionTemplate() {
+    return new PhabricatorAuthMessageTransaction();
+  }
+
+
+/* -(  PhabricatorDestructibleInterface  )----------------------------------- */
+
+
+  public function destroyObjectPermanently(
+    PhabricatorDestructionEngine $engine) {
+    $this->delete();
+  }
+
+}
diff --git a/src/applications/auth/storage/PhabricatorAuthMessageTransaction.php b/src/applications/auth/storage/PhabricatorAuthMessageTransaction.php
new file mode 100644
--- /dev/null
+++ b/src/applications/auth/storage/PhabricatorAuthMessageTransaction.php
@@ -0,0 +1,18 @@
+<?php
+
+final class PhabricatorAuthMessageTransaction
+  extends PhabricatorModularTransaction {
+
+  public function getApplicationName() {
+    return 'auth';
+  }
+
+  public function getApplicationTransactionType() {
+    return PhabricatorAuthMessagePHIDType::TYPECONST;
+  }
+
+  public function getBaseTransactionClass() {
+    return 'PhabricatorAuthMessageTransactionType';
+  }
+
+}
diff --git a/src/applications/auth/xaction/PhabricatorAuthMessageTextTransaction.php b/src/applications/auth/xaction/PhabricatorAuthMessageTextTransaction.php
new file mode 100644
--- /dev/null
+++ b/src/applications/auth/xaction/PhabricatorAuthMessageTextTransaction.php
@@ -0,0 +1,39 @@
+<?php
+
+final class PhabricatorAuthMessageTextTransaction
+  extends PhabricatorAuthMessageTransactionType {
+
+  const TRANSACTIONTYPE = 'text';
+
+  public function generateOldValue($object) {
+    return $object->getMessageText();
+  }
+
+  public function applyInternalEffects($object, $value) {
+    $object->setMessageText($value);
+  }
+
+  public function getTitle() {
+    return pht(
+      '%s updated the message text.',
+      $this->renderAuthor());
+  }
+
+  public function hasChangeDetailView() {
+    return true;
+  }
+
+  public function getMailDiffSectionHeader() {
+    return pht('CHANGES TO MESSAGE');
+  }
+
+  public function newChangeDetailView() {
+    $viewer = $this->getViewer();
+
+    return id(new PhabricatorApplicationTransactionTextDiffDetailView())
+      ->setViewer($viewer)
+      ->setOldText($this->getOldValue())
+      ->setNewText($this->getNewValue());
+  }
+
+}
diff --git a/src/applications/auth/xaction/PhabricatorAuthMessageTransactionType.php b/src/applications/auth/xaction/PhabricatorAuthMessageTransactionType.php
new file mode 100644
--- /dev/null
+++ b/src/applications/auth/xaction/PhabricatorAuthMessageTransactionType.php
@@ -0,0 +1,4 @@
+<?php
+
+abstract class PhabricatorAuthMessageTransactionType
+  extends PhabricatorModularTransactionType {}