diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 02fe5dd5..776be234 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -135,14 +135,21 @@ jobs:
         uses: actions/cache@v4
         with:
           path: ~/.emscripten-cache
-          key: ${{ runner.os }}-emscripten
+          key: ${{ runner.os }}-emscripten-{{ hashFiles('/home/runner/.emscripten-cache/sanity.txt') }}
           restore-keys: |
-            ${{ runner.os }}-emscripten
+            ${{ runner.os }}-emscripten-
 
-      - name: Install dependenciesch
+      - name: Install dependencies
         run: |
           npm ci
 
+      - name: Download MLIR
+        run: |
+          npm run download-mlir
+        env:
+          GH_TOKEN: ${{ github.token }}
+        continue-on-error: true
+
       - name: Prettier
         run: |
           npm -w cxx-frontend run prettier
diff --git a/package.json b/package.json
index de131543..6c3b1289 100644
--- a/package.json
+++ b/package.json
@@ -41,6 +41,7 @@
     "update-tests": "zx scripts/update-tests.mjs",
     "cxx-gen-ast": "node packages/cxx-gen-ast",
     "cxx-gen-lsp": "node packages/cxx-gen-lsp packages/cxx-gen-lsp/metaModel.json packages/cxx-gen-lsp -o src/lsp/cxx/lsp",
-    "download-lsp-model": "zx scripts/download-lsp-model.mjs"
+    "download-lsp-model": "zx scripts/download-lsp-model.mjs",
+    "download-mlir": "gh run download -n mlir --dir build.em/llvm-project/install/"
   }
 }
diff --git a/packages/cxx-frontend/scripts/build.js b/packages/cxx-frontend/scripts/build.js
index b396a384..c3ab30fa 100644
--- a/packages/cxx-frontend/scripts/build.js
+++ b/packages/cxx-frontend/scripts/build.js
@@ -28,6 +28,17 @@ $.verbose = true;
 // get the root directory of the project
 const projectRootSourcePath = path.join(__dirname, "../../..");
 
+const hasMLIR = fs.existsSync(
+  path.join(
+    projectRootSourcePath,
+    "build.em/llvm-project/install/bin/llvm-tblgen.js",
+  ),
+);
+
+if (hasMLIR) {
+  console.log("building with MLIR support");
+}
+
 // get the source path of the cxx-frontend package
 const cxxFrontendSourcePath = path.join(
   projectRootSourcePath,
@@ -108,6 +119,14 @@ async function dockerBuild() {
     );
   }
 
+  if (hasMLIR) {
+    cmakeOptions.push(
+      `-DCXX_ENABLE_MLIR=YES`,
+      `-DLLVM_DIR=/code/build.em/llvm-project/install/lib/cmake/llvm`,
+      `-DMLIR_DIR=/code/build.em/llvm-project/install/lib/cmake/mlir`,
+    );
+  }
+
   const user = await $`id -u`;
 
   await $`mkdir -p ${emscriptenCacheDir}`;
@@ -129,6 +148,14 @@ async function emsdkBuild({ cmake, emcmake, flatc, kwgen }) {
     `-B ${projectRootSourcePath}/build.em`,
   ];
 
+  if (hasMLIR) {
+    cmakeOptions.push(
+      `-DCXX_ENABLE_MLIR=YES`,
+      `-DLLVM_DIR=${projectRootSourcePath}/build.em/llvm-project/install/lib/cmake/llvm`,
+      `-DMLIR_DIR=${projectRootSourcePath}/build.em/llvm-project/install/lib/cmake/mlir`,
+    );
+  }
+
   if (argv.debug) {
     cmakeOptions.push(`-DCMAKE_BUILD_TYPE=Debug`);
   } else {
@@ -146,7 +173,9 @@ async function emsdkBuild({ cmake, emcmake, flatc, kwgen }) {
 async function emsdkBuildPresets() {
   const cmake = await which("cmake", { nothrow: true });
 
-  await $`${cmake} -S ${projectRootSourcePath} --preset emscripten`;
+  const preset = hasMLIR ? "emscripten-mlir" : "emscripten";
+
+  await $`${cmake} -S ${projectRootSourcePath} --preset ${preset}`;
 
   await $`${cmake} --build ${projectRootSourcePath}/build.em --target install`;
 }