diff --git a/Makefile.js b/Makefile.js
index 54ef7060675..519b9943a7c 100644
--- a/Makefile.js
+++ b/Makefile.js
@@ -79,7 +79,7 @@ const NODE = "node ", // intentional extra space
     PERF_MULTIFILES_TARGETS = `"${PERF_MULTIFILES_TARGET_DIR + path.sep}{lib,tests${path.sep}lib}${path.sep}**${path.sep}*.js"`,
 
     // Settings
-    MOCHA_TIMEOUT = 10000;
+    MOCHA_TIMEOUT = parseInt(process.env.ESLINT_MOCHA_TIMEOUT, 10) || 10000;
 
 //------------------------------------------------------------------------------
 // Helpers
diff --git a/docs/developer-guide/unit-tests.md b/docs/developer-guide/unit-tests.md
index 46d77b59076..2968a23805a 100644
--- a/docs/developer-guide/unit-tests.md
+++ b/docs/developer-guide/unit-tests.md
@@ -37,3 +37,7 @@ Running individual tests is useful when you're working on a specific bug and ite
 ## More Control on Unit Testing
 
 `npm run test:cli` is an alias of the Mocha cli in `./node_modules/.bin/mocha`. [Options](https://mochajs.org/#command-line-usage) are available to be provided to help to better control the test to run.
+
+The default timeout for tests in `npm test` is 10000ms. You may change the timeout by providing `ESLINT_MOCHA_TIMEOUT` environment variable, for example:
+
+    ESLINT_MOCHA_TIMEOUT=20000 npm test