diff --git a/hphp/test/run b/hphp/test/run
index f3baa1e..0190423 100755
--- a/hphp/test/run
+++ b/hphp/test/run
@@ -1424,6 +1424,11 @@ function run_and_lock_test($options, $test) {
 }
 
 function run_test($options, $test) {
+  static $timeout_executable_available = null;
+  if (is_null($timeout_executable_available)) {
+    $timeout_executable_available = is_executable('/usr/bin/timeout');
+  }
+
   if (skip_test($options, $test)) return 'skip';
 
   $test_ext = pathinfo($test, PATHINFO_EXTENSION);
@@ -1433,7 +1438,7 @@ function run_test($options, $test) {
     return 'skip';
   }
 
-  if (is_executable('/usr/bin/timeout')) {
+  if ($timeout_executable_available) {
     $hhvm = '/usr/bin/timeout 300 '.$hhvm;
   } else {
     $hhvm = __DIR__.'/../tools/timeout.sh -t 300 '.$hhvm;