diff --git a/fs/walk.ts b/fs/walk.ts
new file mode 100644
index 0000000000..92e4ba593f
--- /dev/null
+++ b/fs/walk.ts
@@ -0,0 +1,134 @@
+import {
+  FileInfo,
+  cwd,
+  readDir,
+  readDirSync,
+  readlink,
+  readlinkSync,
+  stat,
+  statSync
+} from "deno";
+import { relative } from "path.ts";
+
+export interface WalkOptions {
+  maxDepth?: number;
+  exts?: string[];
+  match?: RegExp[];
+  skip?: RegExp[];
+  // FIXME don't use `any` here?
+  onError?: (err: any) => void;
+  followSymlinks?: Boolean;
+}
+
+/** Generate all files in a directory recursively.
+ *
+ *      for await (const fileInfo of walk()) {
+ *        console.log(fileInfo.path);
+ *        assert(fileInfo.isFile());
+ *      };
+ */
+export async function* walk(
+  dir: string = ".",
+  options: WalkOptions = {}
+): AsyncIterableIterator<FileInfo> {
+  options.maxDepth -= 1;
+  let ls: FileInfo[] = [];
+  try {
+    ls = await readDir(dir);
+  } catch (err) {
+    if (options.onError) {
+      options.onError(err);
+    }
+  }
+  for (let f of ls) {
+    if (f.isSymlink()) {
+      if (options.followSymlinks) {
+        f = await resolve(f);
+      } else {
+        continue;
+      }
+    }
+    if (f.isFile()) {
+      if (include(f, options)) {
+        yield f;
+      }
+    } else {
+      if (!(options.maxDepth < 0)) {
+        yield* walk(f.path, options);
+      }
+    }
+  }
+}
+
+/** Generate all files in a directory recursively.
+ *
+ *      for (const fileInfo of walkSync()) {
+ *        console.log(fileInfo.path);
+ *        assert(fileInfo.isFile());
+ *      };
+ */
+export function* walkSync(
+  dir: string = ".",
+  options: WalkOptions = {}
+): IterableIterator<FileInfo> {
+  options.maxDepth -= 1;
+  let ls: FileInfo[] = [];
+  try {
+    ls = readDirSync(dir);
+  } catch (err) {
+    if (options.onError) {
+      options.onError(err);
+    }
+  }
+  for (let f of ls) {
+    if (f.isSymlink()) {
+      if (options.followSymlinks) {
+        f = resolveSync(f);
+      } else {
+        continue;
+      }
+    }
+    if (f.isFile()) {
+      if (include(f, options)) {
+        yield f;
+      }
+    } else {
+      if (!(options.maxDepth < 0)) {
+        yield* walkSync(f.path, options);
+      }
+    }
+  }
+}
+
+function include(f: FileInfo, options: WalkOptions): Boolean {
+  if (options.exts && !options.exts.some(ext => f.path.endsWith(ext))) {
+    return false;
+  }
+  if (options.match && !options.match.some(pattern => pattern.test(f.path))) {
+    return false;
+  }
+  if (options.skip && options.skip.some(pattern => pattern.test(f.path))) {
+    return false;
+  }
+  return true;
+}
+
+async function resolve(f: FileInfo): Promise<FileInfo> {
+  // This is the full path, unfortunately if we were to make it relative
+  // it could resolve to a symlink and cause an infinite loop.
+  const fpath = await readlink(f.path);
+  f = await stat(fpath);
+  // workaround path not being returned by stat
+  f.path = fpath;
+  return f;
+}
+
+function resolveSync(f: FileInfo): FileInfo {
+  // This is the full path, unfortunately if we were to make it relative
+  // it could resolve to a symlink and cause an infinite loop.
+  const fpath = readlinkSync(f.path);
+  f = statSync(fpath);
+  // workaround path not being returned by stat
+  f.path = fpath;
+  return f;
+}
diff --git a/fs/walk_test.ts b/fs/walk_test.ts
new file mode 100644
index 0000000000..7f21a2fb40
--- /dev/null
+++ b/fs/walk_test.ts
@@ -0,0 +1,265 @@
+import {
+  cwd,
+  chdir,
+  FileInfo,
+  makeTempDir,
+  mkdir,
+  open,
+  platform,
+  remove,
+  symlink
+} from "deno";
+
+import { walk, walkSync, WalkOptions } from "./walk.ts";
+import { test, assert, TestFunction } from "../testing/mod.ts";
+
+const isWindows = platform.os === "win";
+
+async function testWalk(
+  setup: (string) => void | Promise<void>,
+  t: TestFunction
+): Promise<void> {
+  const name = t.name;
+  async function fn() {
+    const orig_cwd = cwd();
+    const d = await makeTempDir();
+    chdir(d);
+    try {
+      await setup(d);
+      await t();
+    } finally {
+      chdir(orig_cwd);
+      remove(d, { recursive: true });
+    }
+  }
+  test({ name, fn });
+}
+
+async function walkArray(
+  dirname: string = ".",
+  options: WalkOptions = {}
+): Promise<Array<string>> {
+  const arr: string[] = [];
+  for await (const f of walk(dirname, { ...options })) {
+    arr.push(f.path.replace(/\\/g, "/"));
+  }
+  arr.sort();
+  const arr_sync = Array.from(walkSync(dirname, options), (f: FileInfo) =>
+    f.path.replace(/\\/g, "/")
+  ).sort();
+  assert.equal(arr, arr_sync);
+  return arr;
+}
+
+async function touch(path: string): Promise<void> {
+  await open(path, "w");
+}
+function assertReady(expectedLength: number) {
+  const arr = Array.from(walkSync(), (f: FileInfo) => f.path);
+  assert.equal(arr.length, expectedLength);
+}
+
+testWalk(
+  async (d: string) => {
+    await mkdir(d + "/empty");
+  },
+  async function emptyDir() {
+    const arr = await walkArray();
+    assert.equal(arr.length, 0);
+  }
+);
+
+testWalk(
+  async (d: string) => {
+    await touch(d + "/x");
+  },
+  async function singleFile() {
+    const arr = await walkArray();
+    assert.equal(arr.length, 1);
+    assert.equal(arr[0], "./x");
+  }
+);
+
+testWalk(
+  async (d: string) => {
+    await touch(d + "/x");
+  },
+  async function iteratable() {
+    let count = 0;
+    for (const f of walkSync()) {
+      count += 1;
+    }
+    assert.equal(count, 1);
+    for await (const f of walk()) {
+      count += 1;
+    }
+    assert.equal(count, 2);
+  }
+);
+
+testWalk(
+  async (d: string) => {
+    await mkdir(d + "/a");
+    await touch(d + "/a/x");
+  },
+  async function nestedSingleFile() {
+    const arr = await walkArray();
+    assert.equal(arr.length, 1);
+    assert.equal(arr[0], "./a/x");
+  }
+);
+
+testWalk(
+  async (d: string) => {
+    await mkdir(d + "/a/b/c/d", true);
+    await touch(d + "/a/b/c/d/x");
+  },
+  async function depth() {
+    assertReady(1);
+    const arr_3 = await walkArray(".", { maxDepth: 3 });
+    assert.equal(arr_3.length, 0);
+    const arr_5 = await walkArray(".", { maxDepth: 5 });
+    assert.equal(arr_5.length, 1);
+    assert.equal(arr_5[0], "./a/b/c/d/x");
+  }
+);
+
+testWalk(
+  async (d: string) => {
+    await touch(d + "/x.ts");
+    await touch(d + "/y.rs");
+  },
+  async function ext() {
+    assertReady(2);
+    const arr = await walkArray(".", { exts: [".ts"] });
+    assert.equal(arr.length, 1);
+    assert.equal(arr[0], "./x.ts");
+  }
+);
+
+testWalk(
+  async (d: string) => {
+    await touch(d + "/x.ts");
+    await touch(d + "/y.rs");
+    await touch(d + "/z.py");
+  },
+  async function extAny() {
+    assertReady(3);
+    const arr = await walkArray(".", { exts: [".rs", ".ts"] });
+    assert.equal(arr.length, 2);
+    assert.equal(arr[0], "./x.ts");
+    assert.equal(arr[1], "./y.rs");
+  }
+);
+
+testWalk(
+  async (d: string) => {
+    await touch(d + "/x");
+    await touch(d + "/y");
+  },
+  async function match() {
+    assertReady(2);
+    const arr = await walkArray(".", { match: [/x/] });
+    assert.equal(arr.length, 1);
+    assert.equal(arr[0], "./x");
+  }
+);
+
+testWalk(
+  async (d: string) => {
+    await touch(d + "/x");
+    await touch(d + "/y");
+    await touch(d + "/z");
+  },
+  async function matchAny() {
+    assertReady(3);
+    const arr = await walkArray(".", { match: [/x/, /y/] });
+    assert.equal(arr.length, 2);
+    assert.equal(arr[0], "./x");
+    assert.equal(arr[1], "./y");
+  }
+);
+
+testWalk(
+  async (d: string) => {
+    await touch(d + "/x");
+    await touch(d + "/y");
+  },
+  async function skip() {
+    assertReady(2);
+    const arr = await walkArray(".", { skip: [/x/] });
+    assert.equal(arr.length, 1);
+    assert.equal(arr[0], "./y");
+  }
+);
+
+testWalk(
+  async (d: string) => {
+    await touch(d + "/x");
+    await touch(d + "/y");
+    await touch(d + "/z");
+  },
+  async function skipAny() {
+    assertReady(3);
+    const arr = await walkArray(".", { skip: [/x/, /y/] });
+    assert.equal(arr.length, 1);
+    assert.equal(arr[0], "./z");
+  }
+);
+
+testWalk(
+  async (d: string) => {
+    await mkdir(d + "/a");
+    await mkdir(d + "/b");
+    await touch(d + "/a/x");
+    await touch(d + "/a/y");
+    await touch(d + "/b/z");
+  },
+  async function subDir() {
+    assertReady(3);
+    const arr = await walkArray("b");
+    assert.equal(arr.length, 1);
+    assert.equal(arr[0], "b/z");
+  }
+);
+
+testWalk(async (d: string) => {}, async function onError() {
+  assertReady(0);
+  const ignored = await walkArray("missing");
+  assert.equal(ignored.length, 0);
+  let errors = 0;
+  const arr = await walkArray("missing", { onError: e => (errors += 1) });
+  // It's 2 since walkArray iterates over both sync and async.
+  assert.equal(errors, 2);
+});
+
+testWalk(
+  async (d: string) => {
+    await mkdir(d + "/a");
+    await mkdir(d + "/b");
+    await touch(d + "/a/x");
+    await touch(d + "/a/y");
+    await touch(d + "/b/z");
+    try {
+      await symlink(d + "/b", d + "/a/bb");
+    } catch (err) {
+      assert(isWindows);
+      assert(err.message, "Not implemented");
+    }
+  },
+  async function symlink() {
+    // symlink is not yet implemented on Windows.
+    if (isWindows) {
+      return;
+    }
+
+    assertReady(3);
+    const files = await walkArray("a");
+    assert.equal(files.length, 2);
+    assert(!files.includes("a/bb/z"));
+
+    const arr = await walkArray("a", { followSymlinks: true });
+    assert.equal(arr.length, 3);
+    assert(arr.some(f => f.endsWith("/b/z")));
+  }
+);
diff --git a/test.ts b/test.ts
index 24a1ccc277..dd311c5271 100755
--- a/test.ts
+++ b/test.ts
@@ -13,6 +13,7 @@ import "io/util_test.ts";
 import "io/writers_test.ts";
 import "io/readers_test.ts";
 import "fs/path/test.ts";
+import "fs/walk_test.ts";
 import "io/test.ts";
 import "http/server_test.ts";
 import "http/file_server_test.ts";