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
@@ -408,6 +408,7 @@
     'ArcanistXMLLinterTestCase' => 'lint/linter/__tests__/ArcanistXMLLinterTestCase.php',
     'ArcanistXUnitTestResultParser' => 'unit/parser/ArcanistXUnitTestResultParser.php',
     'CSharpToolsTestEngine' => 'unit/engine/CSharpToolsTestEngine.php',
+    'MidjeUnitTestEngine' => 'unit/engine/MidjeUnitTestEngine.php',
     'NoseTestEngine' => 'unit/engine/NoseTestEngine.php',
     'PhpunitTestEngine' => 'unit/engine/PhpunitTestEngine.php',
     'PhpunitTestEngineTestCase' => 'unit/engine/__tests__/PhpunitTestEngineTestCase.php',
@@ -822,6 +823,7 @@
     'ArcanistXMLLinterTestCase' => 'ArcanistLinterTestCase',
     'ArcanistXUnitTestResultParser' => 'Phobject',
     'CSharpToolsTestEngine' => 'XUnitTestEngine',
+    'MidjeUnitTestEngine' => 'ArcanistUnitTestEngine',
     'NoseTestEngine' => 'ArcanistUnitTestEngine',
     'PhpunitTestEngine' => 'ArcanistUnitTestEngine',
     'PhpunitTestEngineTestCase' => 'PhutilTestCase',
diff --git a/src/unit/engine/MidjeUnitTestEngine.php b/src/unit/engine/MidjeUnitTestEngine.php
new file mode 100644
--- /dev/null
+++ b/src/unit/engine/MidjeUnitTestEngine.php
@@ -0,0 +1,210 @@
+<?php
+
+/**
+ * Very basic unit test engine which runs libphutil tests.
+ */
+final class MidjeUnitTestEngine extends ArcanistUnitTestEngine {
+
+  public function getEngineConfigurationName() {
+    return 'midje';
+  }
+
+  protected function supportsRunAllTests() {
+    return true;
+  }
+
+  public function shouldEchoTestResults() {
+    return false;
+  }
+
+  public function run() {
+    if ($this->getRunAllTests()) {
+      $run_tests = $this->getAllTests();
+    } else {
+      $run_tests = $this->getTestsForPaths();
+    }
+
+    if (!$run_tests) {
+      throw new ArcanistNoEffectException(pht('No tests to run.'));
+    }
+
+    $midje_config = new TempFile();
+    Filesystem::writeFile($midje_config,
+<<<CFG
+(change-defaults
+  :emitter 'midje.emission.plugins.junit
+  :colorize false)
+CFG
+);
+
+    try {
+      list($stdout, $stderr) = execx('lein midje %C :config %s',
+        implode(' ', $run_tests),
+        $midje_config);
+    } catch (CommandException $e) {
+      // Handle only special error codes (see e.g. `man 1 bash` about
+      // "EXIT STATUS")
+      if ($e->getError() > 125) {
+        throw $e;
+      }
+    }
+
+    $results = array();
+    foreach ($run_tests as $test) {
+      $xunit_report = 'target/surefire-reports/TEST-'.$test.'.xml';
+      $cover_report = '';
+
+      $results[] = $this->parseTestResults(
+        $test,
+        $xunit_report,
+        $cover_report);
+    }
+
+    return array_mergev($results);
+  }
+
+  private function parseTestResults($test, $xunit_report, $cover_report) {
+    $xunit_results = Filesystem::readFile($xunit_report);
+    return id(new ArcanistXUnitTestResultParser())
+      ->parseTestResults($xunit_results);
+  }
+
+  private $clojureExtensions = array('clj', 'cljs', 'cljc');
+
+  private function isSupportedFileType($path) {
+    $extension = idx(pathinfo($path), 'extension');
+    foreach ($this->clojureExtensions as $clojure_extension) {
+      if ($extension == $clojure_extension) {
+        return true;
+      }
+    }
+
+    return false;
+  }
+
+  /**
+   * For a given test file, figure out the namespace it contains.
+   *
+   * @param $path  string  Filename with extension
+   * @return string  Namespace
+   */
+  private function testPathToNamespace($path) {
+    $path_stub = $this->stripTestPathPrefix(
+      $this->stripFileExtension($path));
+    $namespace = str_replace('_', '-', $path_stub);
+    $namespace = str_replace('/', '.', $namespace);
+    return $namespace;
+  }
+
+  // FIXME This list should actually be retrieved from `:test-paths` in
+  // "project.clj"
+  private $projectTestPaths = array('test');
+
+  private $testPrefix = 'test_';
+  private $testSuffix = '';
+
+  /**
+   * Remove test path prefix from a file name.
+   *
+   * Tries to remove all known `:test-paths` until one matches.
+   */
+  private function stripTestPathPrefix($path) {
+    foreach ($this->projectTestPaths as $project_test_path) {
+      $prefix = $project_test_path.'/';
+      $prefix_len = strlen($prefix);
+      if (substr($path, 0, $prefix_len) == $prefix) {
+        return substr($path, $prefix_len);
+      }
+    }
+  }
+
+  /**
+   * Small convenience wrapper around `pathinfo()`.
+   */
+  private function stripFileExtension($path) {
+    $path_info = pathinfo($path);
+    return $path_info['dirname'].'/'.$path_info['filename'];
+  }
+
+  /**
+   * For a given path, figure out the corresponding test case's namespace.
+   *
+   * @param $path  string  Path of the file to be tested.
+   * @return string or null  Namespace of the test case, if any.
+   */
+  private function pathToTest($path) {
+    $path_info = pathinfo($path);
+    $base_test_path = $path_info['dirname'].'/'.
+      $this->testPrefix.$path_info['filename'].$this->testSuffix.
+      '.'.$path_info['extension'];
+
+    while ($base_test_path) {
+      foreach ($this->projectTestPaths as $project_test_path) {
+        $test_path = $project_test_path.'/'.$base_test_path;
+        if (is_readable($test_path)) {
+          return $this->testPathToNamespace($test_path);
+        }
+      }
+
+      // FIXME This could be simplified and sped up, if we had `:source-paths`
+      // from "project.clj".
+      $next_pos = strpos($base_test_path, DIRECTORY_SEPARATOR);
+      if (!$next_pos) {
+        return;
+      }
+      $base_test_path = substr($base_test_path, $next_pos + 1);
+    }
+
+    return;
+  }
+
+  /**
+   * Retrieve all test cases.
+   *
+   * @return list<string>  The names of the test case namespaces to be executed.
+   */
+  private function getAllTests() {
+    $test_paths = array();
+    foreach ($this->projectTestPaths as $project_test_path) {
+      foreach ($this->clojureExtensions as $extension) {
+        $test_paths = array_merge($test_paths,
+          glob($project_test_path.'/**/*.'.$extension));
+      }
+    }
+
+    $run_tests = array();
+    foreach ($test_paths as $test_path) {
+      $test = $this->testPathToNamespace($test_path);
+      if ($test) {
+        $run_tests[] = $test;
+      }
+    }
+
+    return $run_tests;
+  }
+
+  /**
+   * Retrieve all relevant test cases.
+   *
+   * For every affected file, it looks for a corresponding test case namespace
+   * with a `-test` suffix.
+   *
+   * @return list<string>  The names of the test case namespaces to be executed.
+   */
+  private function getTestsForPaths() {
+    $run_tests = array();
+    foreach ($this->getPaths() as $path) {
+      if (!$this->isSupportedFileType($path)) {
+        continue;
+      }
+
+      $test = $this->pathToTest($path);
+      if ($test) {
+        $run_tests[] = $test;
+      }
+    }
+
+    return $run_tests;
+  }
+
+}