diff --git a/toolchain/args/BUILD.bazel b/toolchain/args/BUILD.bazel
index e6dc56c..b323589 100644
--- a/toolchain/args/BUILD.bazel
+++ b/toolchain/args/BUILD.bazel
@@ -17,8 +17,8 @@ package(default_visibility = ["//visibility:public"])
 cc_args(
     name = "resource_dir",
     actions = [
+        "@rules_cc//cc/toolchains/actions:compile_actions",
         "@rules_cc//cc/toolchains/actions:link_actions",
-        # We may need it for other actions too?
     ],
     args = [
         "-resource-dir",
@@ -32,6 +32,46 @@ cc_args(
     ],
 )
 
+alias(
+    name = "clang_builtin_headers_include_search_directory",
+    actual = select({
+        "@toolchains_llvm_bootstrapped//platforms/config:linux_x86_64": "@llvm-toolchain-minimal-21.1.8-linux-amd64//:builtin_headers",
+        "@toolchains_llvm_bootstrapped//platforms/config:linux_aarch64": "@llvm-toolchain-minimal-21.1.8-linux-arm64//:builtin_headers",
+        "@toolchains_llvm_bootstrapped//platforms/config:linux_x86_64_gnu": "@llvm-toolchain-minimal-21.1.8-linux-amd64//:builtin_headers",
+        "@toolchains_llvm_bootstrapped//platforms/config:linux_aarch64_gnu": "@llvm-toolchain-minimal-21.1.8-linux-arm64//:builtin_headers",
+        "@toolchains_llvm_bootstrapped//platforms/config:linux_x86_64_musl": "@llvm-toolchain-minimal-21.1.8-linux-amd64//:builtin_headers",
+        "@toolchains_llvm_bootstrapped//platforms/config:linux_aarch64_musl": "@llvm-toolchain-minimal-21.1.8-linux-arm64//:builtin_headers",
+        "@toolchains_llvm_bootstrapped//platforms/config:macos_x86_64": "@llvm-toolchain-minimal-21.1.8-darwin-arm64//:builtin_headers",
+        "@toolchains_llvm_bootstrapped//platforms/config:macos_aarch64": "@llvm-toolchain-minimal-21.1.8-darwin-arm64//:builtin_headers",
+        "@toolchains_llvm_bootstrapped//platforms/config:windows_x86_64": "@llvm-toolchain-minimal-21.1.8-windows-amd64//:builtin_headers",
+        "@toolchains_llvm_bootstrapped//platforms/config:windows_aarch64": "@llvm-toolchain-minimal-21.1.8-windows-arm64//:builtin_headers",
+        "@toolchains_llvm_bootstrapped//platforms/config:none_wasm32": "@llvm-toolchain-minimal-21.1.8-linux-amd64//:builtin_headers",
+        "@toolchains_llvm_bootstrapped//platforms/config:none_wasm64": "@llvm-toolchain-minimal-21.1.8-linux-amd64//:builtin_headers",
+    }),
+    visibility = ["//toolchain:__subpackages__"],
+)
+
+cc_args(
+    name = "clang_builtin_headers_include_search_paths",
+    actions = [
+        "@rules_cc//cc/toolchains/actions:compile_actions",
+        "@rules_cc//cc/toolchains/actions:link_actions",
+    ],
+    args = [
+        "-isystem",
+        "{clang_builtin_headers_include_search_path}",
+    ],
+    format = {
+        "clang_builtin_headers_include_search_path": ":clang_builtin_headers_include_search_directory",
+    },
+    data = [
+        ":clang_builtin_headers_include_search_directory",
+    ],
+    allowlist_include_directories = [
+        ":clang_builtin_headers_include_search_directory",
+    ],
+)
+
 cc_args(
     name = "llvm_target_for_platform",
     actions = [
diff --git a/toolchain/BUILD.bazel b/toolchain/BUILD.bazel
index 6ffc9f7..e02089a 100644
--- a/toolchain/BUILD.bazel
+++ b/toolchain/BUILD.bazel
@@ -100,6 +100,7 @@ cc_args_list(
         "@platforms//os:macos": [],
         "//conditions:default": [
             "//toolchain/args:resource_dir",
+            "//toolchain/args:clang_builtin_headers_include_search_paths",
         ],
     }),
 )
diff --git a/toolchain/llvm/llvm.bzl b/toolchain/llvm/llvm.bzl
index d068085..c152552 100644
--- a/toolchain/llvm/llvm.bzl
+++ b/toolchain/llvm/llvm.bzl
@@ -7,6 +7,7 @@ def declare_llvm_targets(*, suffix = ""):
         name = "builtin_headers",
         # Grab whichever version-specific dir is there.
         path = native.glob(["lib/clang/*"], exclude_directories = 0)[0] + "/include",
+        visibility = ["//visibility:public"],
     )
 
     # Convenient exports