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
@@ -15,8 +15,6 @@
     'ArcanistBackoutWorkflow' => 'workflow/ArcanistBackoutWorkflow.php',
     'ArcanistBaseCommitParser' => 'parser/ArcanistBaseCommitParser.php',
     'ArcanistBaseCommitParserTestCase' => 'parser/__tests__/ArcanistBaseCommitParserTestCase.php',
-    'ArcanistBaseUnitTestEngine' => 'unit/engine/ArcanistBaseUnitTestEngine.php',
-    'ArcanistBaseWorkflow' => 'workflow/ArcanistBaseWorkflow.php',
     'ArcanistBaseXHPASTLinter' => 'lint/linter/ArcanistBaseXHPASTLinter.php',
     'ArcanistBookmarkWorkflow' => 'workflow/ArcanistBookmarkWorkflow.php',
     'ArcanistBranchWorkflow' => 'workflow/ArcanistBranchWorkflow.php',
@@ -220,8 +218,6 @@
     'ArcanistAnoidWorkflow' => 'ArcanistWorkflow',
     'ArcanistBackoutWorkflow' => 'ArcanistWorkflow',
     'ArcanistBaseCommitParserTestCase' => 'ArcanistTestCase',
-    'ArcanistBaseUnitTestEngine' => 'ArcanistUnitTestEngine',
-    'ArcanistBaseWorkflow' => 'ArcanistWorkflow',
     'ArcanistBaseXHPASTLinter' => 'ArcanistFutureLinter',
     'ArcanistBookmarkWorkflow' => 'ArcanistFeatureWorkflow',
     'ArcanistBranchWorkflow' => 'ArcanistFeatureWorkflow',
diff --git a/src/unit/engine/ArcanistBaseUnitTestEngine.php b/src/unit/engine/ArcanistBaseUnitTestEngine.php
deleted file mode 100644
--- a/src/unit/engine/ArcanistBaseUnitTestEngine.php
+++ /dev/null
@@ -1,7 +0,0 @@
-<?php
-
-/**
- * NOTE: Do not extend from this class, extend from
- * @{class:ArcanistUnitTestEngine} instead.
- */
-abstract class ArcanistBaseUnitTestEngine extends ArcanistUnitTestEngine {}
diff --git a/src/unit/engine/ArcanistUnitTestEngine.php b/src/unit/engine/ArcanistUnitTestEngine.php
--- a/src/unit/engine/ArcanistUnitTestEngine.php
+++ b/src/unit/engine/ArcanistUnitTestEngine.php
@@ -51,13 +51,6 @@
   final public function setWorkingCopy(
     ArcanistWorkingCopyIdentity $working_copy) {
 
-    // TODO: Remove this once ArcanistBaseUnitTestEngine is gone.
-    if ($this instanceof ArcanistBaseUnitTestEngine) {
-      phutil_deprecated(
-        'ArcanistBaseUnitTestEngine',
-        pht('You should extend from `%s` instead.', __CLASS__));
-    }
-
     $this->workingCopy = $working_copy;
     return $this;
   }
diff --git a/src/workflow/ArcanistBaseWorkflow.php b/src/workflow/ArcanistBaseWorkflow.php
deleted file mode 100644
--- a/src/workflow/ArcanistBaseWorkflow.php
+++ /dev/null
@@ -1,7 +0,0 @@
-<?php
-
-/**
- * NOTE: Do not extend from this class, extend from @{class:ArcanistWorkflow}
- * instead.
- */
-abstract class ArcanistBaseWorkflow extends ArcanistWorkflow {}
diff --git a/src/workflow/ArcanistWorkflow.php b/src/workflow/ArcanistWorkflow.php
--- a/src/workflow/ArcanistWorkflow.php
+++ b/src/workflow/ArcanistWorkflow.php
@@ -84,15 +84,6 @@
    * whether the command succeeded or failed.
    */
   public function finalize() {
-    // TODO: Remove this once ArcanistBaseWorkflow is gone.
-    if ($this instanceof ArcanistBaseWorkflow) {
-      phutil_deprecated(
-        'ArcanistBaseWorkflow',
-        pht(
-          'You should extend from `%s` instead.',
-          __CLASS__));
-    }
-
     $this->finalizeWorkingCopy();
   }