diff --git a/run-tests.php b/run-tests.php
index 0e3f2bb4cb1..d6c84c667d1 100755
--- a/run-tests.php
+++ b/run-tests.php
@@ -1212,6 +1212,10 @@ function system_with_timeout(
     }
 
     $timeout = $valgrind ? 300 : ($env['TEST_TIMEOUT'] ?? 60);
+    /* ASAN can cause a ~2-3x slowdown. */
+    if (isset($env['SKIP_ASAN'])) {
+        $timeout *= 3;
+    }
 
     while (true) {
         /* hide errors from interrupted syscalls */