diff --git a/xtask/src/main.rs b/xtask/src/main.rs
index 90ce1d7e..6074ff19 100644
--- a/xtask/src/main.rs
+++ b/xtask/src/main.rs
@@ -5,6 +5,7 @@ mod clippy;
 mod fetch;
 mod generate;
 mod test;
+mod upgrade_wasmtime;
 
 use anstyle::{AnsiColor, Color, Style};
 use anyhow::Result;
@@ -37,6 +38,8 @@ enum Commands {
     Test(Test),
     /// Run the WASM test suite
     TestWasm,
+    /// Upgrade the wasmtime dependency.
+    UpgradeWasmtime(UpgradeWasmtime),
 }
 
 #[derive(Args)]
@@ -127,6 +130,13 @@ struct Test {
     nocapture: bool,
 }
 
+#[derive(Args)]
+struct UpgradeWasmtime {
+    /// The version to upgrade to.
+    #[arg(long, short)]
+    version: Version,
+}
+
 const BUILD_VERSION: &str = env!("CARGO_PKG_VERSION");
 const BUILD_SHA: Option<&str> = option_env!("BUILD_SHA");
 const EMSCRIPTEN_VERSION: &str = include_str!("../../cli/loader/emscripten-version");
@@ -189,6 +199,9 @@ fn run() -> Result<()> {
         }
         Commands::Test(test_options) => test::run(&test_options)?,
         Commands::TestWasm => test::run_wasm()?,
+        Commands::UpgradeWasmtime(upgrade_wasmtime_options) => {
+            upgrade_wasmtime::run(&upgrade_wasmtime_options)?;
+        }
     }
 
     Ok(())
diff --git a/xtask/src/upgrade_wasmtime.rs b/xtask/src/upgrade_wasmtime.rs
new file mode 100644
index 00000000..f2584408
--- /dev/null
+++ b/xtask/src/upgrade_wasmtime.rs
@@ -0,0 +1,141 @@
+use std::{path::Path, process::Command};
+
+use anyhow::{Context, Result};
+use git2::Repository;
+use semver::Version;
+
+use crate::UpgradeWasmtime;
+
+const WASMTIME_RELEASE_URL: &str = "https://github.com/bytecodealliance/wasmtime/releases/download";
+
+fn update_cargo(version: &Version) -> Result<()> {
+    let file = std::fs::read_to_string("lib/Cargo.toml")?;
+    let mut old_lines = file.lines();
+    let mut new_lines = Vec::with_capacity(old_lines.size_hint().0);
+
+    while let Some(line) = old_lines.next() {
+        new_lines.push(line.to_string());
+        if line == "[dependencies.wasmtime-c-api]" {
+            let _ = old_lines.next();
+            new_lines.push(format!("version = \"{version}\""));
+        }
+    }
+
+    std::fs::write("lib/Cargo.toml", new_lines.join("\n") + "\n")?;
+
+    Ok(())
+}
+
+fn zig_fetch(lines: &mut Vec<String>, version: &Version, url_suffix: &str) -> Result<()> {
+    let url = &format!("{WASMTIME_RELEASE_URL}/v{version}/wasmtime-v{version}-{url_suffix}");
+    println!("  Fetching {url}");
+    lines.push(format!("      .url = \"{url}\","));
+
+    let output = Command::new("zig")
+        .arg("fetch")
+        .arg(url)
+        .output()
+        .with_context(|| format!("Failed to execute zig fetch {url}"))?;
+
+    let hash = String::from_utf8_lossy(&output.stdout);
+    lines.push(format!("      .hash = \"{}\",", hash.trim_end()));
+
+    Ok(())
+}
+
+fn update_zig(version: &Version) -> Result<()> {
+    let file = std::fs::read_to_string("build.zig.zon")?;
+    let mut old_lines = file.lines();
+    let new_lines = &mut Vec::with_capacity(old_lines.size_hint().0);
+
+    while let Some(line) = old_lines.next() {
+        new_lines.push(line.to_string());
+        match line {
+            "    .wasmtime_c_api_aarch64_android = .{" => {
+                let (_, _) = (old_lines.next(), old_lines.next());
+                zig_fetch(new_lines, version, "aarch64-android-c-api.tar.xz")?;
+            }
+            "    .wasmtime_c_api_aarch64_linux = .{" => {
+                let (_, _) = (old_lines.next(), old_lines.next());
+                zig_fetch(new_lines, version, "aarch64-linux-c-api.tar.xz")?;
+            }
+            "    .wasmtime_c_api_aarch64_macos = .{" => {
+                let (_, _) = (old_lines.next(), old_lines.next());
+                zig_fetch(new_lines, version, "aarch64-macos-c-api.tar.xz")?;
+            }
+            "    .wasmtime_c_api_riscv64gc_linux = .{" => {
+                let (_, _) = (old_lines.next(), old_lines.next());
+                zig_fetch(new_lines, version, "riscv64gc-linux-c-api.tar.xz")?;
+            }
+            "    .wasmtime_c_api_s390x_linux = .{" => {
+                let (_, _) = (old_lines.next(), old_lines.next());
+                zig_fetch(new_lines, version, "s390x-linux-c-api.tar.xz")?;
+            }
+            "    .wasmtime_c_api_x86_64_android = .{" => {
+                let (_, _) = (old_lines.next(), old_lines.next());
+                zig_fetch(new_lines, version, "x86_64-android-c-api.tar.xz")?;
+            }
+            "    .wasmtime_c_api_x86_64_linux = .{" => {
+                let (_, _) = (old_lines.next(), old_lines.next());
+                zig_fetch(new_lines, version, "x86_64-linux-c-api.tar.xz")?;
+            }
+            "    .wasmtime_c_api_x86_64_macos = .{" => {
+                let (_, _) = (old_lines.next(), old_lines.next());
+                zig_fetch(new_lines, version, "x86_64-macos-c-api.tar.xz")?;
+            }
+            "    .wasmtime_c_api_x86_64_mingw = .{" => {
+                let (_, _) = (old_lines.next(), old_lines.next());
+                zig_fetch(new_lines, version, "x86_64-mingw-c-api.zip")?;
+            }
+            "    .wasmtime_c_api_x86_64_musl = .{" => {
+                let (_, _) = (old_lines.next(), old_lines.next());
+                zig_fetch(new_lines, version, "x86_64-musl-c-api.tar.xz")?;
+            }
+            "    .wasmtime_c_api_x86_64_windows = .{" => {
+                let (_, _) = (old_lines.next(), old_lines.next());
+                zig_fetch(new_lines, version, "x86_64-windows-c-api.zip")?;
+            }
+            _ => {}
+        }
+    }
+
+    std::fs::write("build.zig.zon", new_lines.join("\n") + "\n")?;
+
+    Ok(())
+}
+
+fn create_commit(repo: &Repository, version: &Version) -> Result<()> {
+    let mut index = repo.index()?;
+    index.add_path(Path::new("lib/Cargo.toml"))?;
+    index.add_path(Path::new("build.zig.zon"))?;
+    index.write()?;
+
+    let tree_id = index.write_tree()?;
+    let tree = repo.find_tree(tree_id)?;
+    let signature = repo.signature()?;
+    let parent_commit = repo.revparse_single("HEAD")?.peel_to_commit()?;
+
+    let _ = repo.commit(
+        Some("HEAD"),
+        &signature,
+        &signature,
+        &format!("build(deps): bump wasmtime to v{version}"),
+        &tree,
+        &[&parent_commit],
+    )?;
+
+    Ok(())
+}
+
+pub fn run(args: &UpgradeWasmtime) -> Result<()> {
+    println!("Upgrading wasmtime in lib/Cargo.toml");
+    update_cargo(&args.version)?;
+
+    println!("Upgrading wasmtime in build.zig.zon");
+    update_zig(&args.version)?;
+
+    let repo = Repository::open(".")?;
+    create_commit(&repo, &args.version)?;
+
+    Ok(())
+}