diff --git a/scripts/generate.js b/scripts/generate.js
index f54cacf70..79b7e2b17 100644
--- a/scripts/generate.js
+++ b/scripts/generate.js
@@ -35,12 +35,12 @@ const {
 } = require('./utils')
 
 start(minimist(process.argv.slice(2), {
-  string: ['tag']
+  string: ['tag', 'branch']
 }))
 
 function start (opts) {
   const log = ora('Loading Elasticsearch Repository').start()
-  if (semver.valid(opts.tag) === null) {
+  if (opts.branch == null && semver.valid(opts.tag) === null) {
     log.fail(`Missing or invalid tag: ${opts.tag}`)
     return
   }
@@ -55,7 +55,7 @@ function start (opts) {
   log.text = 'Cleaning API folder...'
   rimraf.sync(join(apiOutputFolder, '*.js'))
 
-  cloneAndCheckout({ log, tag: opts.tag }, (err, { apiFolder, xPackFolder }) => {
+  cloneAndCheckout({ log, tag: opts.tag, branch: opts.branch }, (err, { apiFolder, xPackFolder }) => {
     if (err) {
       log.fail(err.message)
       return
diff --git a/scripts/utils/clone-es.js b/scripts/utils/clone-es.js
index 7889541c3..05608eeaa 100644
--- a/scripts/utils/clone-es.js
+++ b/scripts/utils/clone-es.js
@@ -29,7 +29,7 @@ const apiFolder = join(esFolder, 'rest-api-spec', 'src', 'main', 'resources', 'r
 const xPackFolder = join(esFolder, 'x-pack', 'plugin', 'src', 'test', 'resources', 'rest-api-spec', 'api')
 
 function cloneAndCheckout (opts, callback) {
-  const { log, tag } = opts
+  const { log, tag, branch } = opts
   withTag(tag, callback)
 
   /**
@@ -57,13 +57,19 @@ function cloneAndCheckout (opts, callback) {
 
     if (fresh) {
       clone(checkout)
+    } else if (opts.branch) {
+      checkout(true)
     } else {
       checkout()
     }
 
-    function checkout () {
-      log.text = `Checking out tag '${tag}'`
-      git.checkout(tag, err => {
+    function checkout (alsoPull = false) {
+      if (branch) {
+        log.text = `Checking out branch '${branch}'`
+      } else {
+        log.text = `Checking out tag '${tag}'`
+      }
+      git.checkout(branch || tag, err => {
         if (err) {
           if (retry++ > 0) {
             callback(new Error(`Cannot checkout tag '${tag}'`), { apiFolder, xPackFolder })
@@ -71,6 +77,9 @@ function cloneAndCheckout (opts, callback) {
           }
           return pull(checkout)
         }
+        if (alsoPull) {
+          return pull(checkout)
+        }
         callback(null, { apiFolder, xPackFolder })
       })
     }