diff --git a/.arcconfig b/.arcconfig
--- a/.arcconfig
+++ b/.arcconfig
@@ -1,6 +1,6 @@
 {
   "phabricator.uri": "https://secure.phabricator.com/",
-  "unit.engine": "PhutilUnitTestEngine",
+  "unit.engine": "ArcanistConfigurationDrivenTestEngine",
   "load": [
     "src/"
   ]
diff --git a/.arcunit b/.arcunit
new file mode 100644
--- /dev/null
+++ b/.arcunit
@@ -0,0 +1,8 @@
+{
+  "engines": {
+    "phutil": {
+      "type": "phutil",
+      "include": "(\\.php$)"
+    }
+  }
+}
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
@@ -58,6 +58,7 @@
     'ArcanistConcatenationOperatorXHPASTLinterRule' => 'lint/linter/xhpast/rules/ArcanistConcatenationOperatorXHPASTLinterRule.php',
     'ArcanistConfiguration' => 'configuration/ArcanistConfiguration.php',
     'ArcanistConfigurationDrivenLintEngine' => 'lint/engine/ArcanistConfigurationDrivenLintEngine.php',
+    'ArcanistConfigurationDrivenTestEngine' => 'unit/engine/ArcanistConfigurationDrivenTestEngine.php',
     'ArcanistConfigurationManager' => 'configuration/ArcanistConfigurationManager.php',
     'ArcanistConsoleLintRenderer' => 'lint/renderer/ArcanistConsoleLintRenderer.php',
     'ArcanistConstructorParenthesesXHPASTLinterRule' => 'lint/linter/xhpast/rules/ArcanistConstructorParenthesesXHPASTLinterRule.php',
@@ -331,6 +332,7 @@
     'ArcanistConcatenationOperatorXHPASTLinterRule' => 'ArcanistXHPASTLinterRule',
     'ArcanistConfiguration' => 'Phobject',
     'ArcanistConfigurationDrivenLintEngine' => 'ArcanistLintEngine',
+    'ArcanistConfigurationDrivenTestEngine' => 'ArcanistUnitTestEngine',
     'ArcanistConfigurationManager' => 'Phobject',
     'ArcanistConsoleLintRenderer' => 'ArcanistLintRenderer',
     'ArcanistConstructorParenthesesXHPASTLinterRule' => 'ArcanistXHPASTLinterRule',
diff --git a/src/unit/engine/ArcanistConfigurationDrivenTestEngine.php b/src/unit/engine/ArcanistConfigurationDrivenTestEngine.php
new file mode 100644
--- /dev/null
+++ b/src/unit/engine/ArcanistConfigurationDrivenTestEngine.php
@@ -0,0 +1,184 @@
+<?php
+
+final class ArcanistConfigurationDrivenTestEngine
+  extends ArcanistUnitTestEngine {
+
+  protected function supportsRunAllTests() {
+    return true;
+  }
+
+  public function buildTestEngines() {
+    $working_copy = $this->getWorkingCopy();
+    $config_path  = $working_copy->getProjectPath('.arcunit');
+
+    if (!Filesystem::pathExists($config_path)) {
+      throw new ArcanistUsageException(
+        pht(
+          "Unable to find '%s' file to configure test engines. Create an ".
+          "'%s' file in the root directory of the working copy.",
+          '.arcunit',
+          '.arcunit'));
+    }
+
+    $data = Filesystem::readFile($config_path);
+    $config = null;
+    try {
+      $config = phutil_json_decode($data);
+    } catch (PhutilJSONParserException $ex) {
+      throw new PhutilProxyException(
+        pht(
+          "Expected '%s' file to be a valid JSON file, but ".
+          "failed to decode '%s'.",
+          '.arcunit',
+          $config_path),
+        $ex);
+    }
+
+    $test_engines = $this->loadAvailableTestEngines();
+
+    try {
+      PhutilTypeSpec::checkMap(
+        $config,
+        array(
+          'engines' => 'map<string, map<string, wild>>',
+        ));
+    } catch (PhutilTypeCheckException $ex) {
+      throw new PhutilProxyException(
+        pht("Error in parsing '%s' file.", $config_path),
+        $ex);
+    }
+
+    $built_test_engines = array();
+    $all_paths = $this->getPaths();
+
+    foreach ($config['engines'] as $name => $spec) {
+      $type = idx($spec, 'type');
+
+      if ($type !== null) {
+        if (empty($test_engines[$type])) {
+          throw new ArcanistUsageException(
+            pht(
+              "Test engine '%s' specifies invalid type '%s'. ".
+              "Available test engines are: %s.",
+              $name,
+              $type,
+              implode(', ', array_keys($test_engines))));
+        }
+
+        $test_engine = clone $test_engines[$type];
+      } else {
+        // We'll raise an error below about the invalid "type" key.
+        $test_engine = null;
+      }
+
+      try {
+        PhutilTypeSpec::checkMap(
+          $spec,
+          array(
+            'type' => 'string',
+            'include' => 'optional regex | list<regex>',
+            'exclude' => 'optional regex | list<regex>',
+          ));
+      } catch (PhutilTypeCheckException $ex) {
+        throw new PhutilProxyException(
+          pht(
+            "Error in parsing '%s' file, for test engine '%s'.",
+            '.arcunit',
+            $name),
+          $ex);
+      }
+
+      $include = (array)idx($spec, 'include', array());
+      $exclude = (array)idx($spec, 'exclude', array());
+      $paths = $this->matchPaths(
+        $all_paths,
+        $include,
+        $exclude);
+
+      $test_engine->setPaths($paths);
+      $built_test_engines[] = $test_engine;
+    }
+
+    return $built_test_engines;
+  }
+
+  public function run() {
+    $paths = $this->getPaths();
+
+    // If we are running with `--everything` then `$paths` will be `null`.
+    if (!$paths) {
+      $paths = array();
+    }
+
+    $engines    = $this->buildTestEngines();
+    $results    = array();
+    $exceptions = array();
+
+    foreach ($engines as $engine) {
+      $engine
+        ->setWorkingCopy($this->getWorkingCopy())
+        ->setEnableAsyncTests($this->getEnableAsyncTests())
+        ->setEnableCoverage($this->getEnableCoverage());
+
+      if ($engine->supportsRunAllTests()) {
+        $engine->setRunAllTests($this->getRunAllTests());
+      }
+
+      try {
+        $results[] = $engine->run();
+      } catch (ArcanistNoEffectException $ex) {
+        $exceptions[] = $ex;
+      }
+    }
+
+    if (!$results) {
+      // If all engines throw an `ArcanistNoEffectException`, then we should
+      // preserve this behavior.
+      throw new ArcanistNoEffectException(pht('No tests to run.'));
+    }
+
+    return array_mergev($results);
+  }
+
+  private function loadAvailableTestEngines() {
+    return id(new PhutilClassMapQuery())
+      ->setAncestorClass('ArcanistUnitTestEngine')
+      ->setUniqueMethod('getEngineConfigurationName', true)
+      ->execute();
+  }
+
+  private function matchPaths(array $paths, array $include, array $exclude) {
+    $match = array();
+
+    foreach ($paths as $path) {
+      $keep = false;
+      if (!$include) {
+        $keep = true;
+      } else {
+        foreach ($include as $rule) {
+          if (preg_match($rule, $path)) {
+            $keep = true;
+            break;
+          }
+        }
+      }
+
+      if (!$keep) {
+        continue;
+      }
+
+      if ($exclude) {
+        foreach ($exclude as $rule) {
+          if (preg_match($rule, $path)) {
+            continue 2;
+          }
+        }
+      }
+
+      $match[] = $path;
+    }
+
+    return $match;
+  }
+
+}
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
@@ -16,6 +16,10 @@
 
   final public function __construct() {}
 
+  public function getEngineConfigurationName() {
+    return null;
+  }
+
   final public function setRunAllTests($run_all_tests) {
     if (!$this->supportsRunAllTests() && $run_all_tests) {
       throw new Exception(
diff --git a/src/unit/engine/PhutilUnitTestEngine.php b/src/unit/engine/PhutilUnitTestEngine.php
--- a/src/unit/engine/PhutilUnitTestEngine.php
+++ b/src/unit/engine/PhutilUnitTestEngine.php
@@ -5,6 +5,10 @@
  */
 final class PhutilUnitTestEngine extends ArcanistUnitTestEngine {
 
+  public function getEngineConfigurationName() {
+    return 'phutil';
+  }
+
   protected function supportsRunAllTests() {
     return true;
   }