diff --git a/packages/core/parcel-bundler/src/Bundler.js b/packages/core/parcel-bundler/src/Bundler.js
index 98238faa5a2..f30ae772a52 100644
--- a/packages/core/parcel-bundler/src/Bundler.js
+++ b/packages/core/parcel-bundler/src/Bundler.js
@@ -19,7 +19,7 @@ const installPackage = require('./utils/installPackage');
 const bundleReport = require('./utils/bundleReport');
 const prettifyTime = require('./utils/prettifyTime');
 const getRootDir = require('./utils/getRootDir');
-const {glob} = require('./utils/glob');
+const {glob, isGlob} = require('./utils/glob');
 
 /**
  * The Bundler is the main entry point. It resolves and loads assets,
@@ -29,7 +29,9 @@ class Bundler extends EventEmitter {
   constructor(entryFiles, options = {}) {
     super();
 
-    this.entryFiles = this.normalizeEntries(entryFiles);
+    entryFiles = this.normalizeEntries(entryFiles);
+    this.watchedGlobs = entryFiles.filter(entry => isGlob(entry));
+    this.entryFiles = this.findEntryFiles(entryFiles);
     this.options = this.normalizeOptions(options);
 
     this.resolver = new Resolver(this.options);
@@ -82,6 +84,10 @@ class Bundler extends EventEmitter {
       entryFiles = [process.cwd()];
     }
 
+    return entryFiles;
+  }
+
+  findEntryFiles(entryFiles) {
     // Match files as globs
     return entryFiles
       .reduce((p, m) => p.concat(glob.sync(m)), [])
@@ -372,7 +378,12 @@ class Bundler extends EventEmitter {
       if (process.env.NODE_ENV === 'test' && !this.watcher.ready) {
         await new Promise(resolve => this.watcher.once('ready', resolve));
       }
+      this.watchedGlobs.forEach(glob => {
+        this.watcher.add(glob);
+      });
+      this.watcher.on('add', this.onAdd.bind(this));
       this.watcher.on('change', this.onChange.bind(this));
+      this.watcher.on('unlink', this.onUnlink.bind(this));
     }
 
     if (this.options.hmr) {
@@ -758,7 +769,24 @@ class Bundler extends EventEmitter {
     }
   }
 
+  async onAdd(path) {
+    path = Path.join(process.cwd(), path);
+
+    let asset = this.parser.getAsset(path, this.options);
+    this.loadedAssets.set(path, asset);
+
+    this.entryAssets.add(asset);
+
+    await this.watch(path, asset);
+    this.onChange(path);
+  }
+
   async onChange(path) {
+    // The path to the newly-added items are not absolute.
+    if (!Path.isAbsolute(path)) {
+      path = Path.resolve(process.cwd(), path);
+    }
+
     let assets = this.watchedAssets.get(path);
     if (!assets || !assets.size) {
       return;
@@ -779,6 +807,19 @@ class Bundler extends EventEmitter {
     }, 100);
   }
 
+  async onUnlink(path) {
+    // The path to the newly-added items are not absolute.
+    if (!Path.isAbsolute(path)) {
+      path = Path.resolve(process.cwd(), path);
+    }
+
+    let asset = this.getLoadedAsset(path);
+    this.entryAssets.delete(asset);
+    this.unloadAsset(asset);
+
+    this.bundle();
+  }
+
   middleware() {
     this.bundle();
     return Server.middleware(this);
diff --git a/packages/core/parcel-bundler/test/detect-dir-change.js b/packages/core/parcel-bundler/test/detect-dir-change.js
new file mode 100644
index 00000000000..7dd8d9a847f
--- /dev/null
+++ b/packages/core/parcel-bundler/test/detect-dir-change.js
@@ -0,0 +1,129 @@
+const assert = require('assert');
+const Path = require('path');
+const fs = require('@parcel/fs');
+const {sleep, rimraf, ncp, bundler} = require('@parcel/test-utils');
+
+let inputRoot = Path.join(__dirname, 'input', 'detect-dir-change');
+
+describe('detect directory changes', function() {
+  beforeEach(async function() {
+    await rimraf(inputRoot);
+    await fs.mkdirp(inputRoot);
+    await ncp(__dirname + '/integration/detect-dir-change/', inputRoot);
+  });
+
+  describe('when a file matches a glob', async function() {
+    it('should rebuild when the file is added', async function() {
+      // 1. Bundle
+      let b = bundler('test/input/detect-dir-change/src/*.js', {
+        watch: true
+      });
+      await b.bundle();
+
+      assert(await fs.exists(Path.join(__dirname, '/dist/', 'index.js')));
+
+      // We'll check if bundle is called with this listener.
+      let bundled = false;
+      b.on('bundled', () => {
+        bundled = true;
+      });
+
+      // 2. Write file and assert.
+      await fs.writeFile(
+        Path.join(inputRoot, './src/app.js'),
+        "module.exports = function () { return 'app' }"
+      );
+
+      await sleep(1000);
+
+      assert(bundled);
+    });
+
+    it('should rebuild when the file is removed', async function() {
+      // 1. Add file and check the result bundle has all files.
+      let filePath = Path.join(inputRoot, './src/app.js');
+      await fs.writeFile(
+        filePath,
+        "module.exports = function () { return 'app' }"
+      );
+
+      let b = bundler('test/input/detect-dir-change/src/*.js', {
+        watch: true
+      });
+
+      let bundle = await b.bundle();
+
+      let childBundleNames = Array.from(bundle.childBundles.values()).map(
+        bundle => Path.basename(bundle.name)
+      );
+
+      assert(childBundleNames.includes('index.js'));
+      assert(childBundleNames.includes('app.js'));
+
+      // We'll check if bundle is called with this listener.
+      let bundled = false;
+      b.on('bundled', () => {
+        bundled = true;
+      });
+
+      // 2. Check dist file removed correctly.
+      await fs.unlink(filePath);
+
+      await sleep(1000);
+      assert(bundled);
+    });
+  });
+
+  describe('when a file does not match a glob', async function() {
+    it('should not rebuild when the file is added', async function() {
+      // 1. Bundle
+      let b = bundler('test/input/detect-dir-change/src/*.js', {
+        watch: true
+      });
+      await b.bundle();
+
+      assert(await fs.exists(Path.join(__dirname, '/dist/', 'index.js')));
+
+      // We'll check if bundle is called with this listener.
+      let bundled = false;
+      b.on('bundled', () => {
+        bundled = true;
+      });
+
+      // 2. Create unrelated file and assert
+      await fs.writeFile(
+        Path.join(inputRoot, './src/app2.ts'),
+        "module.exports = function () { return 'app' }"
+      );
+
+      await sleep(1000);
+      assert(!bundled);
+    });
+
+    it('should not rebuild when the file is removed', async function() {
+      // 1. Add file and check bundle has all files.
+      let filePath = Path.join(inputRoot, './src/test.html');
+      await fs.writeFile(filePath, '<html></html>');
+
+      let b = bundler('test/input/detect-dir-change/src/*.js', {
+        watch: true
+      });
+
+      let bundle = await b.bundle();
+
+      assert(Path.basename(bundle.name), 'index.js');
+
+      // We'll check if bundle is called with this listener.
+      let bundled = false;
+      b.on('bundled', () => {
+        bundled = true;
+      });
+
+      // 2. Remove file and assert that bundle() isn't called.
+      await fs.unlink(filePath);
+
+      await sleep(1000);
+      assert(!bundled);
+    });
+  });
+});
diff --git a/packages/core/parcel-bundler/test/integration/detect-dir-change/src/index.js b/packages/core/parcel-bundler/test/integration/detect-dir-change/src/index.js
new file mode 100644
index 00000000000..dc1d27ea630
--- /dev/null
+++ b/packages/core/parcel-bundler/test/integration/detect-dir-change/src/index.js
@@ -0,0 +1,3 @@
+module.exports = function() {
+  return 'hello';
+}
\ No newline at end of file