diff --git a/build/toolchain/musl-host-gcc/sysroot/musl.bzl b/build/toolchain/musl-host-gcc/sysroot/musl.bzl
new file mode 100644
index 0000000..5055b83
--- /dev/null
+++ b/build/toolchain/musl-host-gcc/sysroot/musl.bzl
@@ -0,0 +1,44 @@
+#  Copyright 2020 The Monogon Project Authors.
+#
+#  SPDX-License-Identifier: Apache-2.0
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+
+load(
+    "//build/utils:detect_root.bzl",
+    "detect_root",
+)
+
+def _musl_headers(ctx):
+    hdrs_name = ctx.attr.name + "_headers"
+    hdrs_dir = ctx.actions.declare_directory(hdrs_name)
+
+    root = detect_root(ctx.attr.src)
+    ctx.actions.run_shell(
+        inputs = ctx.files.src,
+        outputs = [hdrs_dir],
+        progress_message = "Collecting musl headers",
+        mnemonic = "MuslCollectHeaders",
+        arguments = [root, ctx.attr.arch, hdrs_dir.path],
+        use_default_shell_env = True,
+        command = "make -C \"$1\" install-headers ARCH=\"$2\" includedir=\"$(pwd)/$3\" > /dev/null",
+    )
+    return [DefaultInfo(files=depset([hdrs_dir]))]
+
+musl_headers = rule(
+    implementation = _musl_headers,
+    attrs = {
+        "src": attr.label(mandatory = True),
+        "arch": attr.string(mandatory = True),
+    },
+)