diff --git a/packages/metro/src/commands/build.js b/packages/metro/src/commands/build.js
index 6de007a6..bd0c6e0f 100644
--- a/packages/metro/src/commands/build.js
+++ b/packages/metro/src/commands/build.js
@@ -15,8 +15,6 @@
 const MetroApi = require('..');
 const TerminalReporter = require('../lib/TerminalReporter');
 
-const os = require('os');
-
 const {makeAsyncCommand} = require('../cli-utils');
 const {Terminal} = require('metro-core');
 
@@ -35,11 +33,7 @@ exports.builder = (yargs: Yargs) => {
   yargs.option('platform', {alias: 'p', type: 'string'});
   yargs.option('output-type', {alias: 't', type: 'string'});
 
-  yargs.option('max-workers', {
-    alias: 'j',
-    type: 'number',
-    default: Math.max(1, Math.floor(os.cpus().length)),
-  });
+  yargs.option('max-workers', {alias: 'j', type: 'number'});
 
   yargs.option('optimize', {alias: 'z', type: 'boolean'});
   yargs.option('dev', {alias: 'g', type: 'boolean'});
diff --git a/packages/metro/src/commands/serve.js b/packages/metro/src/commands/serve.js
index 7f9e6cb4..92a61569 100644
--- a/packages/metro/src/commands/serve.js
+++ b/packages/metro/src/commands/serve.js
@@ -14,8 +14,6 @@
 
 const MetroApi = require('..');
 
-const os = require('os');
-
 const {watchFile, makeAsyncCommand} = require('../cli-utils');
 const {promisify} = require('util');
 
@@ -33,11 +31,7 @@ exports.builder = (yargs: Yargs) => {
   yargs.option('host', {alias: 'h', type: 'string', default: 'localhost'});
   yargs.option('port', {alias: 'p', type: 'number', default: 8080});
 
-  yargs.option('max-workers', {
-    alias: 'j',
-    type: 'number',
-    default: Math.max(1, Math.floor(os.cpus().length)),
-  });
+  yargs.option('max-workers', {alias: 'j', type: 'number'});
 
   yargs.option('secure', {type: 'boolean'});
   yargs.option('secure-key', {type: 'string'});
diff --git a/packages/metro/src/index.js b/packages/metro/src/index.js
index 89d5e698..d6499b7e 100644
--- a/packages/metro/src/index.js
+++ b/packages/metro/src/index.js
@@ -22,6 +22,7 @@ const TransformCaching = require('./lib/TransformCaching');
 const attachWebsocketServer = require('./lib/attachWebsocketServer');
 const defaults = require('./defaults');
 const fs = require('fs');
+const getMaxWorkers = require('./lib/getMaxWorkers');
 const http = require('http');
 const https = require('https');
 const path = require('path');
@@ -78,7 +79,7 @@ async function asyncRealpath(path): Promise<string> {
 async function runMetro({
   config,
   resetCache = false,
-  maxWorkers = 1,
+  maxWorkers = getMaxWorkers(),
   // $FlowFixMe TODO t0 https://github.com/facebook/flow/issues/183
   port = null,
   reporter = new TerminalReporter(new Terminal(process.stdout)),