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
@@ -184,6 +184,7 @@
     'ArcanistTodoWorkflow' => 'workflow/ArcanistTodoWorkflow.php',
     'ArcanistUncommittedChangesException' => 'exception/usage/ArcanistUncommittedChangesException.php',
     'ArcanistUnitConsoleRenderer' => 'unit/renderer/ArcanistUnitConsoleRenderer.php',
+    'ArcanistUnitJSONRealtimeRenderer' => 'unit/renderer/ArcanistUnitJSONRealtimeRenderer.php',
     'ArcanistUnitRenderer' => 'unit/renderer/ArcanistUnitRenderer.php',
     'ArcanistUnitTestEngine' => 'unit/engine/ArcanistUnitTestEngine.php',
     'ArcanistUnitTestResult' => 'unit/ArcanistUnitTestResult.php',
@@ -366,6 +367,7 @@
     'ArcanistTodoWorkflow' => 'ArcanistWorkflow',
     'ArcanistUncommittedChangesException' => 'ArcanistUsageException',
     'ArcanistUnitConsoleRenderer' => 'ArcanistUnitRenderer',
+    'ArcanistUnitJSONRealtimeRenderer' => 'ArcanistUnitRenderer',
     'ArcanistUnitTestableLintEngine' => 'ArcanistLintEngine',
     'ArcanistUnitWorkflow' => 'ArcanistWorkflow',
     'ArcanistUpgradeWorkflow' => 'ArcanistWorkflow',
diff --git a/src/unit/renderer/ArcanistUnitJSONRealtimeRenderer.php b/src/unit/renderer/ArcanistUnitJSONRealtimeRenderer.php
new file mode 100644
--- /dev/null
+++ b/src/unit/renderer/ArcanistUnitJSONRealtimeRenderer.php
@@ -0,0 +1,13 @@
+<?php
+
+final class ArcanistUnitJSONRealtimeRenderer extends ArcanistUnitRenderer {
+
+  public function renderUnitResult(ArcanistUnitTestResult $result) {
+    return '##arc-unit## '.json_encode($result->toDictionary())."\n";
+  }
+
+  public function renderPostponedResult($count) {
+    return null;
+  }
+
+}
diff --git a/src/workflow/ArcanistUnitWorkflow.php b/src/workflow/ArcanistUnitWorkflow.php
--- a/src/workflow/ArcanistUnitWorkflow.php
+++ b/src/workflow/ArcanistUnitWorkflow.php
@@ -75,6 +75,9 @@
         'help' =>
           "With 'full', show full pretty report (Default). ".
           "With 'json', report results in JSON format. ".
+          "With 'json-realtime', report results in JSON format as ".
+          "test results occur (JSON entries separated by newlines ".
+          "and prefixed with '##arc-unit## '). ".
           "With 'ugly', use uglier (but more efficient) JSON formatting. ".
           "With 'none', don't print results. ",
         'conflicts' => array(
@@ -153,7 +156,13 @@
     }
     $this->engine->setArguments($this->getPassthruArgumentsAsMap('unit'));
 
-    $renderer = new ArcanistUnitConsoleRenderer();
+    $output_format = $this->getOutputFormat();
+
+    if ($output_format === 'json-realtime') {
+      $renderer = new ArcanistUnitJSONRealtimeRenderer();
+    } else {
+      $renderer = new ArcanistUnitConsoleRenderer();
+    }
     $this->engine->setRenderer($renderer);
 
     $enable_coverage = null; // Means "default".
@@ -177,9 +186,7 @@
 
     $console = PhutilConsole::getConsole();
 
-    $output_format = $this->getOutputFormat();
-
-    if ($output_format !== 'full') {
+    if ($output_format !== 'full' && $output_format !== 'json-realtime') {
       $console->disableOut();
     }
 
@@ -268,7 +275,7 @@
       }
     }
 
-    if ($output_format !== 'full') {
+    if ($output_format !== 'full' && $output_format !== 'json-realtime') {
       $console->enableOut();
     }
     $data = array_values(mpull($results, 'toDictionary'));
@@ -351,6 +358,7 @@
     $known_formats = array(
       'none' => 'none',
       'json' => 'json',
+      'json-realtime' => 'json-realtime',
       'ugly' => 'ugly',
       'full' => 'full',
     );