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
@@ -296,7 +296,6 @@
     'DifferentialAdjustmentMapTestCase' => 'applications/differential/storage/__tests__/DifferentialAdjustmentMapTestCase.php',
     'DifferentialAffectedPath' => 'applications/differential/storage/DifferentialAffectedPath.php',
     'DifferentialApplyPatchField' => 'applications/differential/customfield/DifferentialApplyPatchField.php',
-    'DifferentialArcanistProjectField' => 'applications/differential/customfield/DifferentialArcanistProjectField.php',
     'DifferentialAsanaRepresentationField' => 'applications/differential/customfield/DifferentialAsanaRepresentationField.php',
     'DifferentialAuditorsField' => 'applications/differential/customfield/DifferentialAuditorsField.php',
     'DifferentialAuthorField' => 'applications/differential/customfield/DifferentialAuthorField.php',
@@ -368,10 +367,8 @@
     'DifferentialGetAllDiffsConduitAPIMethod' => 'applications/differential/conduit/DifferentialGetAllDiffsConduitAPIMethod.php',
     'DifferentialGetCommitMessageConduitAPIMethod' => 'applications/differential/conduit/DifferentialGetCommitMessageConduitAPIMethod.php',
     'DifferentialGetCommitPathsConduitAPIMethod' => 'applications/differential/conduit/DifferentialGetCommitPathsConduitAPIMethod.php',
-    'DifferentialGetDiffConduitAPIMethod' => 'applications/differential/conduit/DifferentialGetDiffConduitAPIMethod.php',
     'DifferentialGetRawDiffConduitAPIMethod' => 'applications/differential/conduit/DifferentialGetRawDiffConduitAPIMethod.php',
     'DifferentialGetRevisionCommentsConduitAPIMethod' => 'applications/differential/conduit/DifferentialGetRevisionCommentsConduitAPIMethod.php',
-    'DifferentialGetRevisionConduitAPIMethod' => 'applications/differential/conduit/DifferentialGetRevisionConduitAPIMethod.php',
     'DifferentialGetWorkingCopy' => 'applications/differential/DifferentialGetWorkingCopy.php',
     'DifferentialGitHubLandingStrategy' => 'applications/differential/landing/DifferentialGitHubLandingStrategy.php',
     'DifferentialGitSVNIDField' => 'applications/differential/customfield/DifferentialGitSVNIDField.php',
@@ -3542,7 +3539,6 @@
     'DifferentialAdjustmentMapTestCase' => 'ArcanistPhutilTestCase',
     'DifferentialAffectedPath' => 'DifferentialDAO',
     'DifferentialApplyPatchField' => 'DifferentialCustomField',
-    'DifferentialArcanistProjectField' => 'DifferentialCustomField',
     'DifferentialAsanaRepresentationField' => 'DifferentialCustomField',
     'DifferentialAuditorsField' => 'DifferentialStoredCustomField',
     'DifferentialAuthorField' => 'DifferentialCustomField',
@@ -3618,10 +3614,8 @@
     'DifferentialGetAllDiffsConduitAPIMethod' => 'DifferentialConduitAPIMethod',
     'DifferentialGetCommitMessageConduitAPIMethod' => 'DifferentialConduitAPIMethod',
     'DifferentialGetCommitPathsConduitAPIMethod' => 'DifferentialConduitAPIMethod',
-    'DifferentialGetDiffConduitAPIMethod' => 'DifferentialConduitAPIMethod',
     'DifferentialGetRawDiffConduitAPIMethod' => 'DifferentialConduitAPIMethod',
     'DifferentialGetRevisionCommentsConduitAPIMethod' => 'DifferentialConduitAPIMethod',
-    'DifferentialGetRevisionConduitAPIMethod' => 'DifferentialConduitAPIMethod',
     'DifferentialGitHubLandingStrategy' => 'DifferentialLandingStrategy',
     'DifferentialGitSVNIDField' => 'DifferentialCustomField',
     'DifferentialHostField' => 'DifferentialCustomField',
diff --git a/src/applications/differential/conduit/DifferentialCreateDiffConduitAPIMethod.php b/src/applications/differential/conduit/DifferentialCreateDiffConduitAPIMethod.php
--- a/src/applications/differential/conduit/DifferentialCreateDiffConduitAPIMethod.php
+++ b/src/applications/differential/conduit/DifferentialCreateDiffConduitAPIMethod.php
@@ -12,7 +12,6 @@
   }
 
   protected function defineParamTypes() {
-
     $vcs_const = $this->formatStringConstants(
       array(
         'svn',
@@ -40,7 +39,7 @@
       'sourceControlPath'         => 'required string',
       'sourceControlBaseRevision' => 'required string',
       'creationMethod'            => 'optional string',
-      'arcanistProject'           => 'optional string',
+      'arcanistProject'           => 'deprecated',
       'lintStatus'                => 'required '.$status_const,
       'unitStatus'                => 'required '.$status_const,
       'repositoryPHID'            => 'optional phid',
@@ -84,21 +83,6 @@
       }
     }
 
-    $project_name = $request->getValue('arcanistProject');
-    $project_phid = null;
-    if ($project_name) {
-      $arcanist_project = id(new PhabricatorRepositoryArcanistProject())
-        ->loadOneWhere(
-          'name = %s',
-          $project_name);
-      if (!$arcanist_project) {
-        $arcanist_project = new PhabricatorRepositoryArcanistProject();
-        $arcanist_project->setName($project_name);
-        $arcanist_project->save();
-      }
-      $project_phid = $arcanist_project->getPHID();
-    }
-
     switch ($request->getValue('lintStatus')) {
       case 'skip':
         $lint_status = DifferentialLintStatus::LINT_SKIP;
@@ -156,7 +140,6 @@
       'sourceControlPath' => $request->getValue('sourceControlPath'),
       'sourceControlBaseRevision' =>
         $request->getValue('sourceControlBaseRevision'),
-      'arcanistProjectPHID' => $project_phid,
       'lintStatus' => $lint_status,
       'unitStatus' => $unit_status,
     );
diff --git a/src/applications/differential/conduit/DifferentialGetDiffConduitAPIMethod.php b/src/applications/differential/conduit/DifferentialGetDiffConduitAPIMethod.php
deleted file mode 100644
--- a/src/applications/differential/conduit/DifferentialGetDiffConduitAPIMethod.php
+++ /dev/null
@@ -1,81 +0,0 @@
-<?php
-
-final class DifferentialGetDiffConduitAPIMethod
-  extends DifferentialConduitAPIMethod {
-
-  public function getAPIMethodName() {
-    return 'differential.getdiff';
-  }
-
-  public function shouldAllowPublic() {
-    return true;
-  }
-
-  public function getMethodStatus() {
-    return self::METHOD_STATUS_DEPRECATED;
-  }
-
-  public function getMethodStatusDescription() {
-    return pht(
-      'This method has been deprecated in favor of differential.querydiffs.');
-  }
-
-
-  public function getMethodDescription() {
-    return pht('Load the content of a diff from Differential by revision id '.
-               'or diff id.');
-  }
-
-  protected function defineParamTypes() {
-    return array(
-      'revision_id' => 'optional id',
-      'diff_id'     => 'optional id',
-    );
-  }
-
-  protected function defineReturnType() {
-    return 'nonempty dict';
-  }
-
-  protected function defineErrorTypes() {
-    return array(
-      'ERR_BAD_DIFF'        => 'No such diff exists.',
-    );
-  }
-
-  protected function execute(ConduitAPIRequest $request) {
-    $diff_id = $request->getValue('diff_id');
-
-    // If we have a revision ID, we need the most recent diff. Figure that out
-    // without loading all the attached data.
-    $revision_id = $request->getValue('revision_id');
-    if ($revision_id) {
-      $diffs = id(new DifferentialDiffQuery())
-        ->setViewer($request->getUser())
-        ->withRevisionIDs(array($revision_id))
-        ->execute();
-      if ($diffs) {
-        $diff_id = head($diffs)->getID();
-      } else {
-        throw new ConduitException('ERR_BAD_DIFF');
-      }
-    }
-
-    $diff = null;
-    if ($diff_id) {
-      $diff = id(new DifferentialDiffQuery())
-        ->setViewer($request->getUser())
-        ->withIDs(array($diff_id))
-        ->needChangesets(true)
-        ->needArcanistProjects(true)
-        ->executeOne();
-    }
-
-    if (!$diff) {
-      throw new ConduitException('ERR_BAD_DIFF');
-    }
-
-    return $diff->getDiffDict();
-  }
-
-}
diff --git a/src/applications/differential/conduit/DifferentialGetRevisionConduitAPIMethod.php b/src/applications/differential/conduit/DifferentialGetRevisionConduitAPIMethod.php
deleted file mode 100644
--- a/src/applications/differential/conduit/DifferentialGetRevisionConduitAPIMethod.php
+++ /dev/null
@@ -1,103 +0,0 @@
-<?php
-
-final class DifferentialGetRevisionConduitAPIMethod
-  extends DifferentialConduitAPIMethod {
-
-  public function getAPIMethodName() {
-    return 'differential.getrevision';
-  }
-
-  public function getMethodStatus() {
-    return self::METHOD_STATUS_DEPRECATED;
-  }
-
-  public function getMethodStatusDescription() {
-    return "Replaced by 'differential.query'.";
-  }
-
-  public function getMethodDescription() {
-    return 'Load the content of a revision from Differential.';
-  }
-
-  protected function defineParamTypes() {
-    return array(
-      'revision_id' => 'required id',
-    );
-  }
-
-  protected function defineReturnType() {
-    return 'nonempty dict';
-  }
-
-  protected function defineErrorTypes() {
-    return array(
-      'ERR_BAD_REVISION'    => 'No such revision exists.',
-    );
-  }
-
-  protected function execute(ConduitAPIRequest $request) {
-    $diff = null;
-
-    $revision_id = $request->getValue('revision_id');
-    $revision = id(new DifferentialRevisionQuery())
-      ->withIDs(array($revision_id))
-      ->setViewer($request->getUser())
-      ->needRelationships(true)
-      ->needReviewerStatus(true)
-      ->executeOne();
-
-    if (!$revision) {
-      throw new ConduitException('ERR_BAD_REVISION');
-    }
-
-    $reviewer_phids = array_values($revision->getReviewers());
-
-    $diffs = id(new DifferentialDiffQuery())
-      ->setViewer($request->getUser())
-      ->withRevisionIDs(array($revision_id))
-      ->needChangesets(true)
-      ->needArcanistProjects(true)
-      ->execute();
-    $diff_dicts = mpull($diffs, 'getDiffDict');
-
-    $commit_dicts = array();
-    $commit_phids = $revision->loadCommitPHIDs();
-    $handles = id(new PhabricatorHandleQuery())
-      ->setViewer($request->getUser())
-      ->withPHIDs($commit_phids)
-      ->execute();
-
-    foreach ($commit_phids as $commit_phid) {
-      $commit_dicts[] = array(
-        'fullname'      => $handles[$commit_phid]->getFullName(),
-        'dateCommitted' => $handles[$commit_phid]->getTimestamp(),
-      );
-    }
-
-    $field_data = $this->loadCustomFieldsForRevisions(
-      $request->getUser(),
-      array($revision));
-
-    $dict = array(
-      'id' => $revision->getID(),
-      'phid' => $revision->getPHID(),
-      'authorPHID' => $revision->getAuthorPHID(),
-      'uri' => PhabricatorEnv::getURI('/D'.$revision->getID()),
-      'title' => $revision->getTitle(),
-      'status' => $revision->getStatus(),
-      'statusName'  =>
-        ArcanistDifferentialRevisionStatus::getNameForRevisionStatus(
-          $revision->getStatus()),
-      'summary' => $revision->getSummary(),
-      'testPlan' => $revision->getTestPlan(),
-      'lineCount' => $revision->getLineCount(),
-      'reviewerPHIDs' => $reviewer_phids,
-      'diffs' => $diff_dicts,
-      'commits' => $commit_dicts,
-      'auxiliary' => idx($field_data, $revision->getPHID(), array()),
-    );
-
-    return $dict;
-  }
-
-}
diff --git a/src/applications/differential/conduit/DifferentialQueryConduitAPIMethod.php b/src/applications/differential/conduit/DifferentialQueryConduitAPIMethod.php
--- a/src/applications/differential/conduit/DifferentialQueryConduitAPIMethod.php
+++ b/src/applications/differential/conduit/DifferentialQueryConduitAPIMethod.php
@@ -44,7 +44,6 @@
       'subscribers'       => 'optional list<phid>',
       'responsibleUsers'  => 'optional list<phid>',
       'branches'          => 'optional list<string>',
-      'arcanistProjects'  => 'optional list<string>',
     );
   }
 
@@ -73,7 +72,6 @@
     $subscribers        = $request->getValue('subscribers');
     $responsible_users  = $request->getValue('responsibleUsers');
     $branches           = $request->getValue('branches');
-    $arc_projects       = $request->getValue('arcanistProjects');
 
     $query = id(new DifferentialRevisionQuery())
       ->setViewer($request->getUser());
@@ -169,19 +167,6 @@
     if ($branches) {
       $query->withBranches($branches);
     }
-    if ($arc_projects) {
-      // This is sort of special-cased, but don't make arc do an extra round
-      // trip.
-      $projects = id(new PhabricatorRepositoryArcanistProject())
-        ->loadAllWhere(
-          'name in (%Ls)',
-          $arc_projects);
-      if (!$projects) {
-        return array();
-      }
-
-      $query->withArcanistProjectPHIDs(mpull($projects, 'getPHID'));
-    }
 
     $query->needRelationships(true);
     $query->needCommitPHIDs(true);
@@ -228,7 +213,6 @@
         'ccs'                 => array_values($revision->getCCPHIDs()),
         'hashes'              => $revision->getHashes(),
         'auxiliary'           => idx($field_data, $phid, array()),
-        'arcanistProjectPHID' => $diff->getArcanistProjectPHID(),
         'repositoryPHID'      => $diff->getRepositoryPHID(),
       );
 
diff --git a/src/applications/differential/conduit/DifferentialQueryDiffsConduitAPIMethod.php b/src/applications/differential/conduit/DifferentialQueryDiffsConduitAPIMethod.php
--- a/src/applications/differential/conduit/DifferentialQueryDiffsConduitAPIMethod.php
+++ b/src/applications/differential/conduit/DifferentialQueryDiffsConduitAPIMethod.php
@@ -33,7 +33,6 @@
         ->withIDs($ids)
         ->withRevisionIDs($revision_ids)
         ->needChangesets(true)
-        ->needArcanistProjects(true)
         ->execute();
     }
 
diff --git a/src/applications/differential/controller/DifferentialRevisionViewController.php b/src/applications/differential/controller/DifferentialRevisionViewController.php
--- a/src/applications/differential/controller/DifferentialRevisionViewController.php
+++ b/src/applications/differential/controller/DifferentialRevisionViewController.php
@@ -33,7 +33,6 @@
     $diffs = id(new DifferentialDiffQuery())
       ->setViewer($request->getUser())
       ->withRevisionIDs(array($this->revisionID))
-      ->needArcanistProjects(true)
       ->execute();
     $diffs = array_reverse($diffs, $preserve_keys = true);
 
diff --git a/src/applications/differential/customfield/DifferentialArcanistProjectField.php b/src/applications/differential/customfield/DifferentialArcanistProjectField.php
deleted file mode 100644
--- a/src/applications/differential/customfield/DifferentialArcanistProjectField.php
+++ /dev/null
@@ -1,42 +0,0 @@
-<?php
-
-final class DifferentialArcanistProjectField
-  extends DifferentialCustomField {
-
-  public function getFieldKey() {
-    return 'differential:arcanist-project';
-  }
-
-  public function getFieldName() {
-    return pht('Arcanist Project');
-  }
-
-  public function getFieldDescription() {
-    return pht('Shows arcanist project name.');
-  }
-
-  public function shouldAppearInPropertyView() {
-    return true;
-  }
-
-  public function renderPropertyViewLabel() {
-    return $this->getFieldName();
-  }
-
-  public function getRequiredHandlePHIDsForPropertyView() {
-    $phid = $this->getArcanistProjectPHID();
-    if ($phid) {
-      return array($phid);
-    }
-    return array();
-  }
-
-  public function renderPropertyViewValue(array $handles) {
-    return $this->renderHandleList($handles);
-  }
-
-  private function getArcanistProjectPHID() {
-    return $this->getObject()->getActiveDiff()->getArcanistProjectPHID();
-  }
-
-}
diff --git a/src/applications/differential/editor/DifferentialDiffEditor.php b/src/applications/differential/editor/DifferentialDiffEditor.php
--- a/src/applications/differential/editor/DifferentialDiffEditor.php
+++ b/src/applications/differential/editor/DifferentialDiffEditor.php
@@ -234,8 +234,7 @@
       ->setSourceControlPath(idx($dict, 'sourceControlPath'))
       ->setSourceControlBaseRevision(idx($dict, 'sourceControlBaseRevision'))
       ->setLintStatus(idx($dict, 'lintStatus'))
-      ->setUnitStatus(idx($dict, 'unitStatus'))
-      ->setArcanistProjectPHID(idx($dict, 'arcanistProjectPHID'));
+      ->setUnitStatus(idx($dict, 'unitStatus'));
 
     return $diff;
   }
diff --git a/src/applications/differential/editor/DifferentialTransactionEditor.php b/src/applications/differential/editor/DifferentialTransactionEditor.php
--- a/src/applications/differential/editor/DifferentialTransactionEditor.php
+++ b/src/applications/differential/editor/DifferentialTransactionEditor.php
@@ -220,7 +220,6 @@
         } else {
           $object->setRepositoryPHID($diff->getRepositoryPHID());
         }
-        $object->setArcanistProjectPHID($diff->getArcanistProjectPHID());
         $object->attachActiveDiff($diff);
 
         // TODO: Update the `diffPHID` once we add that.
diff --git a/src/applications/differential/query/DifferentialDiffQuery.php b/src/applications/differential/query/DifferentialDiffQuery.php
--- a/src/applications/differential/query/DifferentialDiffQuery.php
+++ b/src/applications/differential/query/DifferentialDiffQuery.php
@@ -7,7 +7,6 @@
   private $phids;
   private $revisionIDs;
   private $needChangesets = false;
-  private $needArcanistProjects = false;
 
   public function withIDs(array $ids) {
     $this->ids = $ids;
@@ -29,11 +28,6 @@
     return $this;
   }
 
-  public function needArcanistProjects($bool) {
-    $this->needArcanistProjects = $bool;
-    return $this;
-  }
-
   protected function loadPage() {
     $table = new DifferentialDiff();
     $conn_r = $table->establishConnection('r');
@@ -79,10 +73,6 @@
       $diffs = $this->loadChangesets($diffs);
     }
 
-    if ($diffs && $this->needArcanistProjects) {
-      $diffs = $this->loadArcanistProjects($diffs);
-    }
-
     return $diffs;
   }
 
@@ -98,29 +88,6 @@
     return $diffs;
   }
 
-  private function loadArcanistProjects(array $diffs) {
-    $phids = array_filter(mpull($diffs, 'getArcanistProjectPHID'));
-    $projects = array();
-    $project_map = array();
-    if ($phids) {
-      $projects = id(new PhabricatorRepositoryArcanistProject())
-        ->loadAllWhere(
-          'phid IN (%Ls)',
-          $phids);
-      $project_map = mpull($projects, null, 'getPHID');
-    }
-
-    foreach ($diffs as $diff) {
-      $project = null;
-      if ($diff->getArcanistProjectPHID()) {
-        $project = idx($project_map, $diff->getArcanistProjectPHID());
-      }
-      $diff->attachArcanistProject($project);
-    }
-
-    return $diffs;
-  }
-
   protected function buildWhereClause(AphrontDatabaseConnection $conn_r) {
     $where = array();
 
diff --git a/src/applications/differential/query/DifferentialRepositoryLookup.php b/src/applications/differential/query/DifferentialRepositoryLookup.php
--- a/src/applications/differential/query/DifferentialRepositoryLookup.php
+++ b/src/applications/differential/query/DifferentialRepositoryLookup.php
@@ -22,22 +22,6 @@
     $viewer = $this->viewer;
     $diff = $this->diff;
 
-    // Look for an explicit Arcanist project.
-    if ($diff->getArcanistProjectPHID()) {
-      $project = id(new PhabricatorRepositoryArcanistProject())->loadOneWhere(
-        'phid = %s',
-        $diff->getArcanistProjectPHID());
-      if ($project && $project->getRepositoryID()) {
-        $repositories = id(new PhabricatorRepositoryQuery())
-          ->setViewer($viewer)
-          ->withIDs(array($project->getRepositoryID()))
-          ->execute();
-        if ($repositories) {
-          return head($repositories);
-        }
-      }
-    }
-
     // Look for a repository UUID.
     if ($diff->getRepositoryUUID()) {
       $repositories = id(new PhabricatorRepositoryQuery())
diff --git a/src/applications/differential/query/DifferentialRevisionQuery.php b/src/applications/differential/query/DifferentialRevisionQuery.php
--- a/src/applications/differential/query/DifferentialRevisionQuery.php
+++ b/src/applications/differential/query/DifferentialRevisionQuery.php
@@ -36,7 +36,6 @@
   private $phids = array();
   private $responsibles = array();
   private $branches = array();
-  private $arcanistProjectPHIDs = array();
   private $repositoryPHIDs;
   private $updatedEpochMin;
   private $updatedEpochMax;
@@ -228,19 +227,6 @@
   }
 
 
-  /**
-   * Filter results to only return revisions with a given set of arcanist
-   * projects.
-   *
-   * @param array List of project PHIDs.
-   * @return this
-   * @task config
-   */
-  public function withArcanistProjectPHIDs(array $arc_project_phids) {
-    $this->arcanistProjectPHIDs = $arc_project_phids;
-    return $this;
-  }
-
   public function withRepositoryPHIDs(array $repository_phids) {
     $this->repositoryPHIDs = $repository_phids;
     return $this;
@@ -771,13 +757,6 @@
         $this->branches);
     }
 
-    if ($this->arcanistProjectPHIDs) {
-      $where[] = qsprintf(
-        $conn_r,
-        'r.arcanistProjectPHID in (%Ls)',
-        $this->arcanistProjectPHIDs);
-    }
-
     if ($this->updatedEpochMin !== null) {
       $where[] = qsprintf(
         $conn_r,
diff --git a/src/applications/differential/storage/DifferentialDiff.php b/src/applications/differential/storage/DifferentialDiff.php
--- a/src/applications/differential/storage/DifferentialDiff.php
+++ b/src/applications/differential/storage/DifferentialDiff.php
@@ -262,7 +262,6 @@
       'lintStatus' => $this->getLintStatus(),
       'changes' => array(),
       'properties' => array(),
-      'projectName' => $this->getArcanistProjectName(),
     );
 
     $dict['changes'] = $this->buildChangesList();
diff --git a/src/applications/repository/worker/commitmessageparser/PhabricatorRepositoryCommitMessageParserWorker.php b/src/applications/repository/worker/commitmessageparser/PhabricatorRepositoryCommitMessageParserWorker.php
--- a/src/applications/repository/worker/commitmessageparser/PhabricatorRepositoryCommitMessageParserWorker.php
+++ b/src/applications/repository/worker/commitmessageparser/PhabricatorRepositoryCommitMessageParserWorker.php
@@ -321,14 +321,6 @@
         $this->repository->getCallsign().
         $this->commit->getCommitIdentifier());
 
-    // TODO: This is not correct in SVN where one repository can have multiple
-    // Arcanist projects.
-    $arcanist_project = id(new PhabricatorRepositoryArcanistProject())
-      ->loadOneWhere('repositoryID = %d LIMIT 1', $this->repository->getID());
-    if ($arcanist_project) {
-      $diff->setArcanistProjectPHID($arcanist_project->getPHID());
-    }
-
     $parents = DiffusionQuery::callConduitWithDiffusionRequest(
       $viewer,
       $drequest,