diff --git a/Cargo.lock b/Cargo.lock
index 0eb0b74a07..ea8cb56aed 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2808,6 +2808,16 @@ dependencies = [
  "winapi",
 ]
 
+[[package]]
+name = "tokio"
+version = "1.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "83f0c8e7c0addab50b663055baf787d0af7f413a46e6e7fb9559a4e4db7137a5"
+dependencies = [
+ "autocfg 1.0.1",
+ "pin-project-lite",
+]
+
 [[package]]
 name = "toml"
 version = "0.5.8"
@@ -3041,6 +3051,16 @@ version = "0.10.2+wasi-snapshot-preview1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "fd6fbd9a79829dd1ad0cc20627bf1ed606756a7f77edff7b66b7064f9cb327c6"
 
+[[package]]
+name = "wasi-cap-std-async"
+version = "0.26.0"
+dependencies = [
+ "tokio",
+ "wasi-cap-std-sync",
+ "wasi-common",
+ "wiggle",
+]
+
 [[package]]
 name = "wasi-cap-std-sync"
 version = "0.26.0"
@@ -3059,6 +3079,7 @@ dependencies = [
  "tracing",
  "unsafe-io",
  "wasi-common",
+ "wiggle",
  "winapi",
 ]
 
diff --git a/Cargo.toml b/Cargo.toml
index ffff6d865e..7c8c352b48 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -78,6 +78,7 @@ members = [
   "crates/wiggle/wasmtime",
   "crates/wasi-common",
   "crates/wasi-common/cap-std-sync",
+  "crates/wasi-common/cap-std-async",
   "examples/fib-debug/wasm",
   "examples/wasi/wasm",
   "fuzz",
diff --git a/crates/wasi-common/cap-std-async/Cargo.toml b/crates/wasi-common/cap-std-async/Cargo.toml
new file mode 100644
index 0000000000..471ca5640b
--- /dev/null
+++ b/crates/wasi-common/cap-std-async/Cargo.toml
@@ -0,0 +1,18 @@
+[package]
+name = "wasi-cap-std-async"
+version = "0.26.0"
+authors = ["The Wasmtime Project Developers"]
+description = "WASI implementation in Rust"
+license = "Apache-2.0 WITH LLVM-exception"
+categories = ["wasm"]
+keywords = ["webassembly", "wasm"]
+repository = "https://github.com/bytecodealliance/wasmtime"
+readme = "README.md"
+edition = "2018"
+include = ["src/**/*", "LICENSE" ]
+
+[dependencies]
+wasi-common = { path = "../", version = "0.26.0" }
+wasi-cap-std-sync = { path = "../cap-std-sync", version = "0.26.0" }
+wiggle = { path = "../../wiggle", version = "0.26.0" }
+tokio = { version = "1.5.0", features = [ "rt", "time" ] }
diff --git a/crates/wasi-common/cap-std-async/src/lib.rs b/crates/wasi-common/cap-std-async/src/lib.rs
new file mode 100644
index 0000000000..f01d832c8f
--- /dev/null
+++ b/crates/wasi-common/cap-std-async/src/lib.rs
@@ -0,0 +1,111 @@
+use std::cell::RefCell;
+use std::path::Path;
+use std::rc::Rc;
+pub use wasi_cap_std_sync::{clocks_ctx, random_ctx, Dir};
+use wasi_common::{Table, WasiCtx};
+
+pub fn sched_ctx() -> Box<dyn wasi_common::WasiSched> {
+    use wasi_common::{
+        sched::{Duration, Poll, WasiSched},
+        Error,
+    };
+    struct AsyncSched;
+
+    #[wiggle::async_trait]
+    impl WasiSched for AsyncSched {
+        async fn poll_oneoff<'a>(&self, _poll: &'_ Poll<'a>) -> Result<(), Error> {
+            todo!()
+        }
+        async fn sched_yield(&self) -> Result<(), Error> {
+            tokio::task::yield_now().await;
+            Ok(())
+        }
+        async fn sleep(&self, duration: Duration) -> Result<(), Error> {
+            tokio::time::sleep(duration).await;
+            Ok(())
+        }
+    }
+
+    Box::new(AsyncSched)
+}
+
+pub struct WasiCtxBuilder(wasi_common::WasiCtxBuilder);
+
+impl WasiCtxBuilder {
+    pub fn new() -> Self {
+        WasiCtxBuilder(WasiCtx::builder(
+            random_ctx(),
+            clocks_ctx(),
+            sched_ctx(),
+            Rc::new(RefCell::new(Table::new())),
+        ))
+    }
+    pub fn env(self, var: &str, value: &str) -> Result<Self, wasi_common::StringArrayError> {
+        let s = self.0.env(var, value)?;
+        Ok(WasiCtxBuilder(s))
+    }
+    pub fn envs(self, env: &[(String, String)]) -> Result<Self, wasi_common::StringArrayError> {
+        let mut s = self;
+        for (k, v) in env {
+            s = s.env(k, v)?;
+        }
+        Ok(s)
+    }
+    pub fn inherit_env(self) -> Result<Self, wasi_common::StringArrayError> {
+        let mut s = self.0;
+        for (key, value) in std::env::vars() {
+            s = s.env(&key, &value)?;
+        }
+        Ok(WasiCtxBuilder(s))
+    }
+    pub fn arg(self, arg: &str) -> Result<Self, wasi_common::StringArrayError> {
+        let s = self.0.arg(arg)?;
+        Ok(WasiCtxBuilder(s))
+    }
+    pub fn args(self, arg: &[String]) -> Result<Self, wasi_common::StringArrayError> {
+        let mut s = self;
+        for a in arg {
+            s = s.arg(&a)?;
+        }
+        Ok(s)
+    }
+    pub fn inherit_args(self) -> Result<Self, wasi_common::StringArrayError> {
+        let mut s = self.0;
+        for arg in std::env::args() {
+            s = s.arg(&arg)?;
+        }
+        Ok(WasiCtxBuilder(s))
+    }
+    pub fn stdin(self, f: Box<dyn wasi_common::WasiFile>) -> Self {
+        WasiCtxBuilder(self.0.stdin(f))
+    }
+    pub fn stdout(self, f: Box<dyn wasi_common::WasiFile>) -> Self {
+        WasiCtxBuilder(self.0.stdout(f))
+    }
+    pub fn stderr(self, f: Box<dyn wasi_common::WasiFile>) -> Self {
+        WasiCtxBuilder(self.0.stderr(f))
+    }
+    pub fn inherit_stdin(self) -> Self {
+        self.stdin(Box::new(wasi_cap_std_sync::stdio::stdin()))
+    }
+    pub fn inherit_stdout(self) -> Self {
+        self.stdout(Box::new(wasi_cap_std_sync::stdio::stdout()))
+    }
+    pub fn inherit_stderr(self) -> Self {
+        self.stderr(Box::new(wasi_cap_std_sync::stdio::stderr()))
+    }
+    pub fn inherit_stdio(self) -> Self {
+        self.inherit_stdin().inherit_stdout().inherit_stderr()
+    }
+    pub fn preopened_dir(
+        self,
+        dir: Dir,
+        guest_path: impl AsRef<Path>,
+    ) -> Result<Self, wasi_common::Error> {
+        let dir = Box::new(wasi_cap_std_sync::dir::Dir::from_cap_std(dir));
+        Ok(WasiCtxBuilder(self.0.preopened_dir(dir, guest_path)?))
+    }
+    pub fn build(self) -> Result<WasiCtx, wasi_common::Error> {
+        self.0.build()
+    }
+}