diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index e749aeba85..aafce1f410 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -126,10 +126,12 @@ jobs:
           cargo clippy -p sample_spellchecker &&
           cargo clippy -p sample_uiautomation &&
           cargo clippy -p sample_xml &&
+          cargo clippy -p windows_aarch64_gnullvm &&
           cargo clippy -p windows_aarch64_msvc &&
           cargo clippy -p windows_i686_gnu &&
           cargo clippy -p windows_i686_msvc &&
           cargo clippy -p windows_x86_64_gnu &&
+          cargo clippy -p windows_x86_64_gnullvm &&
           cargo clippy -p windows_x86_64_msvc &&
           cargo clippy -p test_agile &&
           cargo clippy -p test_agile_reference &&
@@ -184,6 +186,7 @@ jobs:
           cargo clippy -p test_winrt &&
           cargo clippy -p tool_bindings &&
           cargo clippy -p tool_gnu &&
+          cargo clippy -p tool_gnullvm &&
           cargo clippy -p tool_ilrs &&
           cargo clippy -p tool_lib &&
           cargo clippy -p tool_msvc &&
diff --git a/.github/workflows/cross-compile.yml b/.github/workflows/cross-compile.yml
index 844a284f59..16a05211bf 100644
--- a/.github/workflows/cross-compile.yml
+++ b/.github/workflows/cross-compile.yml
@@ -8,6 +8,7 @@ on:
 
 env:
   RUSTFLAGS: -Dwarnings
+  LLVM-MINGW-TOOLCHAIN-NAME: llvm-mingw-20220323-ucrt-ubuntu-18.04-x86_64
 
 jobs:
   test:
@@ -27,7 +28,7 @@ jobs:
         #
         image: [macos-latest, ubuntu-latest]
         version: [stable, nightly]
-        target: [x86_64-pc-windows-gnu]
+        target: [x86_64-pc-windows-gnu, aarch64-pc-windows-gnullvm, x86_64-pc-windows-gnullvm]
     runs-on: ${{ matrix.image }}
 
     steps:
@@ -36,6 +37,13 @@ jobs:
 
       - name: Add toolchain target
         run: rustup target add ${{ matrix.target }}
+        if: contains(matrix.target, 'gnullvm') == false
+
+      - name: Add nightly toolchain with rust-src
+        run: |
+          rustup default ${{ matrix.version }}
+          rustup component add rust-src
+        if: startsWith(matrix.image, 'ubuntu-') && contains(matrix.target, 'gnullvm') && matrix.version == 'nightly'
 
       - name: Install gcc-mingw-w64-x86-64
         run: sudo apt-get install -y gcc-mingw-w64-x86-64
@@ -45,6 +53,26 @@ jobs:
         run: brew install mingw-w64
         if: startsWith(matrix.image, 'macos-') && matrix.target == 'x86_64-pc-windows-gnu'
 
+      - name: LLVM MinGW toolchain cache configuration
+        id: cache-llvm-mingw-toolchain
+        uses: actions/cache@v3
+        if: startsWith(matrix.image, 'ubuntu-') && contains(matrix.target, 'gnullvm') && matrix.version == 'nightly'
+        with:
+          path: ${{ env.LLVM-MINGW-TOOLCHAIN-NAME }}
+          key: ${{ env.LLVM-MINGW-TOOLCHAIN-NAME }}
+
+      - name: Install LLVM MinGW toolchain
+        if: startsWith(matrix.image, 'ubuntu-') && contains(matrix.target, 'gnullvm') && matrix.version == 'nightly' && steps.cache-llvm-mingw-toolchain.outputs.cache-hit != 'true'
+        run: |
+          curl -L -o ${{ env.LLVM-MINGW-TOOLCHAIN-NAME }}.tar.xz https://github.com/mstorsjo/llvm-mingw/releases/download/20220323/${{ env.LLVM-MINGW-TOOLCHAIN-NAME }}.tar.xz
+          tar -xf ${{ env.LLVM-MINGW-TOOLCHAIN-NAME }}.tar.xz
+          echo "${{ env.LLVM-MINGW-TOOLCHAIN-NAME }}/bin" >> $GITHUB_PATH
+          
+      - name: Add LLVM MinGW toolchain to PATH
+        if: startsWith(matrix.image, 'ubuntu-') && contains(matrix.target, 'gnullvm') && matrix.version == 'nightly'
+        run: |
+          echo "${{ env.LLVM-MINGW-TOOLCHAIN-NAME }}/bin" >> $GITHUB_PATH
+
       - name: Test
         shell: pwsh
         run: |
@@ -52,3 +80,13 @@ jobs:
           if (-Not (Resolve-Path "target/*/debug/deps/test_win32-*.exe" | Test-Path)) {
             throw "Failed to find test_win32 executable."
           }
+        if: contains(matrix.target, 'gnullvm') == false
+
+      - name: Test with build-std
+        shell: pwsh
+        run: |
+          cargo test --no-run --target ${{ matrix.target }} -Z build-std -p test_win32
+          if (-Not (Resolve-Path "target/*/debug/deps/test_win32-*.exe" | Test-Path)) {
+            throw "Failed to find test_win32 executable."
+          }
+        if: startsWith(matrix.image, 'ubuntu-') && contains(matrix.target, 'gnullvm') && matrix.version == 'nightly'
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index d65c4a4c9a..93f86e7ccf 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -109,10 +109,12 @@ jobs:
           cargo test --target ${{ matrix.target }} -p sample_spellchecker &&
           cargo test --target ${{ matrix.target }} -p sample_uiautomation &&
           cargo test --target ${{ matrix.target }} -p sample_xml &&
+          cargo test --target ${{ matrix.target }} -p windows_aarch64_gnullvm &&
           cargo test --target ${{ matrix.target }} -p windows_aarch64_msvc &&
           cargo test --target ${{ matrix.target }} -p windows_i686_gnu &&
           cargo test --target ${{ matrix.target }} -p windows_i686_msvc &&
           cargo test --target ${{ matrix.target }} -p windows_x86_64_gnu &&
+          cargo test --target ${{ matrix.target }} -p windows_x86_64_gnullvm &&
           cargo test --target ${{ matrix.target }} -p windows_x86_64_msvc &&
           cargo test --target ${{ matrix.target }} -p test_agile &&
           cargo test --target ${{ matrix.target }} -p test_agile_reference &&
@@ -168,6 +170,7 @@ jobs:
           cargo test --target ${{ matrix.target }} -p test_winrt &&
           cargo test --target ${{ matrix.target }} -p tool_bindings &&
           cargo test --target ${{ matrix.target }} -p tool_gnu &&
+          cargo test --target ${{ matrix.target }} -p tool_gnullvm &&
           cargo test --target ${{ matrix.target }} -p tool_ilrs &&
           cargo test --target ${{ matrix.target }} -p tool_lib &&
           cargo test --target ${{ matrix.target }} -p tool_msvc &&
diff --git a/crates/libs/sys/Cargo.toml b/crates/libs/sys/Cargo.toml
index 7db1b7f981..7121d0968f 100644
--- a/crates/libs/sys/Cargo.toml
+++ b/crates/libs/sys/Cargo.toml
@@ -33,6 +33,9 @@ windows_aarch64_msvc = { path = "../../targets/aarch64_msvc", version = "0.39.0"
 [target.aarch64-uwp-windows-msvc.dependencies]
 windows_aarch64_msvc = { path = "../../targets/aarch64_msvc", version = "0.39.0" }
 
+[target.aarch64-pc-windows-gnullvm.dependencies]
+windows_aarch64_gnullvm = { path = "../../targets/aarch64_gnullvm", version = "0.39.0" }
+
 [target.i686-pc-windows-gnu.dependencies]
 windows_i686_gnu = { path = "../../targets/i686_gnu", version = "0.39.0" }
 
@@ -45,6 +48,9 @@ windows_x86_64_gnu = { path = "../../targets/x86_64_gnu", version = "0.39.0" }
 [target.x86_64-uwp-windows-gnu.dependencies]
 windows_x86_64_gnu = { path = "../../targets/x86_64_gnu", version = "0.39.0" }
 
+[target.x86_64-pc-windows-gnullvm.dependencies]
+windows_x86_64_gnullvm = { path = "../../targets/x86_64_gnullvm", version = "0.39.0" }
+
 [features]
 default = []
 deprecated = []
diff --git a/crates/libs/windows/Cargo.toml b/crates/libs/windows/Cargo.toml
index bc389f0402..cb4f17726e 100644
--- a/crates/libs/windows/Cargo.toml
+++ b/crates/libs/windows/Cargo.toml
@@ -33,6 +33,9 @@ windows_aarch64_msvc = { path = "../../targets/aarch64_msvc", version = "0.39.0"
 [target.aarch64-uwp-windows-msvc.dependencies]
 windows_aarch64_msvc = { path = "../../targets/aarch64_msvc", version = "0.39.0" }
 
+[target.aarch64-pc-windows-gnullvm.dependencies]
+windows_aarch64_gnullvm = { path = "../../targets/aarch64_gnullvm", version = "0.39.0" }
+
 [target.i686-pc-windows-gnu.dependencies]
 windows_i686_gnu = { path = "../../targets/i686_gnu", version = "0.39.0" }
 
@@ -45,6 +48,9 @@ windows_x86_64_gnu = { path = "../../targets/x86_64_gnu", version = "0.39.0" }
 [target.x86_64-uwp-windows-gnu.dependencies]
 windows_x86_64_gnu = { path = "../../targets/x86_64_gnu", version = "0.39.0" }
 
+[target.x86_64-pc-windows-gnullvm.dependencies]
+windows_x86_64_gnullvm = { path = "../../targets/x86_64_gnullvm", version = "0.39.0" }
+
 [dependencies]
 windows-implement = { path = "../implement",  version = "0.39.0", optional = true }
 windows-interface = { path = "../interface",  version = "0.39.0", optional = true }
diff --git a/crates/targets/aarch64_gnullvm/Cargo.toml b/crates/targets/aarch64_gnullvm/Cargo.toml
new file mode 100644
index 0000000000..ec8ebcb433
--- /dev/null
+++ b/crates/targets/aarch64_gnullvm/Cargo.toml
@@ -0,0 +1,12 @@
+[package]
+name = "windows_aarch64_gnullvm"
+version = "0.39.0"
+authors = ["Microsoft"]
+edition = "2018"
+license = "MIT OR Apache-2.0"
+description = "Code gen support for the windows crate"
+repository = "https://github.com/microsoft/windows-rs"
+
+[package.metadata.docs.rs]
+default-target = "x86_64-pc-windows-msvc"
+targets = []
diff --git a/crates/targets/aarch64_gnullvm/build.rs b/crates/targets/aarch64_gnullvm/build.rs
new file mode 100644
index 0000000000..8c8f98f5ec
--- /dev/null
+++ b/crates/targets/aarch64_gnullvm/build.rs
@@ -0,0 +1,10 @@
+fn main() {
+    let target = std::env::var("TARGET").unwrap();
+    if target != "aarch64-pc-windows-gnullvm" {
+        return;
+    }
+
+    let dir = std::env::var("CARGO_MANIFEST_DIR").unwrap();
+
+    println!("cargo:rustc-link-search=native={}", std::path::Path::new(&dir).join("lib").display());
+}
diff --git a/crates/targets/aarch64_gnullvm/lib/libwindows.a b/crates/targets/aarch64_gnullvm/lib/libwindows.a
new file mode 100644
index 0000000000..6e771720a1
Binary files /dev/null and b/crates/targets/aarch64_gnullvm/lib/libwindows.a differ
diff --git a/crates/targets/aarch64_gnullvm/src/lib.rs b/crates/targets/aarch64_gnullvm/src/lib.rs
new file mode 100644
index 0000000000..0c9ac1ac8e
--- /dev/null
+++ b/crates/targets/aarch64_gnullvm/src/lib.rs
@@ -0,0 +1 @@
+#![no_std]
diff --git a/crates/targets/x86_64_gnullvm/Cargo.toml b/crates/targets/x86_64_gnullvm/Cargo.toml
new file mode 100644
index 0000000000..a024fba981
--- /dev/null
+++ b/crates/targets/x86_64_gnullvm/Cargo.toml
@@ -0,0 +1,12 @@
+[package]
+name = "windows_x86_64_gnullvm"
+version = "0.39.0"
+authors = ["Microsoft"]
+edition = "2018"
+license = "MIT OR Apache-2.0"
+description = "Code gen support for the windows crate"
+repository = "https://github.com/microsoft/windows-rs"
+
+[package.metadata.docs.rs]
+default-target = "x86_64-pc-windows-msvc"
+targets = []
diff --git a/crates/targets/x86_64_gnullvm/build.rs b/crates/targets/x86_64_gnullvm/build.rs
new file mode 100644
index 0000000000..ea83354fad
--- /dev/null
+++ b/crates/targets/x86_64_gnullvm/build.rs
@@ -0,0 +1,10 @@
+fn main() {
+    let target = std::env::var("TARGET").unwrap();
+    if target != "x86_64-pc-windows-gnullvm" {
+        return;
+    }
+
+    let dir = std::env::var("CARGO_MANIFEST_DIR").unwrap();
+
+    println!("cargo:rustc-link-search=native={}", std::path::Path::new(&dir).join("lib").display());
+}
diff --git a/crates/targets/x86_64_gnullvm/lib/libwindows.a b/crates/targets/x86_64_gnullvm/lib/libwindows.a
new file mode 100644
index 0000000000..57b3dd97a8
Binary files /dev/null and b/crates/targets/x86_64_gnullvm/lib/libwindows.a differ
diff --git a/crates/targets/x86_64_gnullvm/src/lib.rs b/crates/targets/x86_64_gnullvm/src/lib.rs
new file mode 100644
index 0000000000..0c9ac1ac8e
--- /dev/null
+++ b/crates/targets/x86_64_gnullvm/src/lib.rs
@@ -0,0 +1 @@
+#![no_std]
diff --git a/crates/tools/gnullvm/Cargo.toml b/crates/tools/gnullvm/Cargo.toml
new file mode 100644
index 0000000000..76732c0f2c
--- /dev/null
+++ b/crates/tools/gnullvm/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "tool_gnullvm"
+version = "0.0.0"
+edition = "2018"
+publish = false
+
+[dependencies]
+lib = { package = "tool_lib", path = "../lib" }
diff --git a/crates/tools/gnullvm/readme.md b/crates/tools/gnullvm/readme.md
new file mode 100644
index 0000000000..48752c888f
--- /dev/null
+++ b/crates/tools/gnullvm/readme.md
@@ -0,0 +1,8 @@
+The Windows umbrella lib (targeting mingw-w64 LLVM tooling) is generated using the following steps:
+
+0. Ensure MSYS2 MinGW environment is installed (https://www.mingw-w64.org/downloads/)
+1. Execute: `C:\msys64\clang64.exe`
+2. Execute: `pacman -Syuu --noconfirm` (repeat until no further updates available)
+3. Execute `pacman --needed -S mingw-w64-clang-x86_64-toolchain`
+4. Navigate to crate root
+5. Execute: `PATH=$(cygpath -u $USERPROFILE)/.cargo/bin:$PATH cargo +nightly run -p tool_gnullvm --target x86_64-pc-windows-gnullvm -Z build-std -- all`
diff --git a/crates/tools/gnullvm/src/main.rs b/crates/tools/gnullvm/src/main.rs
new file mode 100644
index 0000000000..69acd3df42
--- /dev/null
+++ b/crates/tools/gnullvm/src/main.rs
@@ -0,0 +1,106 @@
+use std::collections::BTreeMap;
+use std::io::prelude::*;
+
+fn main() {
+    let mut cmd = std::process::Command::new("where");
+    cmd.arg("llvm-dlltool.exe");
+
+    let output = cmd.output().unwrap();
+
+    if !output.status.success() {
+        println!("llvm-dlltool.exe not found");
+        return;
+    }
+
+    let target = std::env::args().collect::<Vec<_>>();
+    let mut platform_and_target = vec![];
+    if target.iter().any(|x| x == "x86_64") || target.iter().any(|x| x == "all") {
+        platform_and_target.push(("x86_64_gnullvm", "i386:x86-64"));
+    }
+    if target.iter().any(|x| x == "aarch64") || target.iter().any(|x| x == "all") {
+        platform_and_target.push(("aarch64_gnullvm", "arm64"));
+    }
+    if platform_and_target.is_empty() {
+        println!("Please specify at least one architecture or use 'all' argument");
+        return;
+    };
+
+    let libraries = lib::libraries();
+
+    for (platform, dlltool_target) in platform_and_target {
+        let output = std::path::PathBuf::from(format!("crates/targets/{}/lib", platform));
+        let _ = std::fs::remove_dir_all(&output);
+        std::fs::create_dir_all(&output).unwrap();
+
+        for (library, functions) in &libraries {
+            build_library(&output, library, functions, dlltool_target);
+        }
+
+        build_mri(&output, &libraries);
+
+        for library in libraries.keys() {
+            std::fs::remove_file(output.join(format!("lib{}.a", library))).unwrap();
+        }
+    }
+}
+
+fn build_library(output: &std::path::Path, library: &str, functions: &BTreeMap<String, usize>, dlltool_target: &str) {
+    println!("{}", library);
+
+    // Note that we don't use set_extension as it confuses PathBuf when the library name includes a period.
+    let def_path = output.join(format!("{}.def", library));
+    let mut def = std::fs::File::create(&def_path).unwrap();
+
+    def.write_all(
+        format!(
+            r#"
+LIBRARY {}
+EXPORTS
+"#,
+            library
+        )
+        .as_bytes(),
+    )
+    .unwrap();
+
+    for function in functions.keys() {
+        def.write_all(format!("{}\n", function).as_bytes()).unwrap();
+    }
+
+    drop(def);
+
+    let mut cmd = std::process::Command::new("llvm-dlltool");
+    cmd.current_dir(&output);
+
+    cmd.arg("-m");
+    cmd.arg(dlltool_target);
+    cmd.arg("-d");
+    cmd.arg(format!("{}.def", library));
+    cmd.arg("-l");
+    cmd.arg(format!("lib{}.a", library));
+    cmd.output().unwrap();
+
+    std::fs::remove_file(output.join(format!("{}.def", library))).unwrap();
+}
+
+fn build_mri(output: &std::path::Path, libraries: &BTreeMap<String, BTreeMap<String, usize>>) {
+    let mri_path = output.join("unified.mri");
+    let mut mri = std::fs::File::create(&mri_path).unwrap();
+    println!("Generating {}", mri_path.to_string_lossy());
+
+    mri.write_all(b"CREATE libwindows.a\n").unwrap();
+
+    for library in libraries.keys() {
+        mri.write_all(format!("ADDLIB lib{}.a\n", library).as_bytes()).unwrap();
+    }
+
+    mri.write_all(b"SAVE\nEND\n").unwrap();
+
+    let mut cmd = std::process::Command::new("llvm-ar");
+    cmd.current_dir(&output);
+    cmd.arg("-M");
+    cmd.stdin(std::fs::File::open(&mri_path).unwrap());
+    cmd.output().unwrap();
+
+    std::fs::remove_file(&mri_path).unwrap();
+}
diff --git a/crates/tools/sys/src/main.rs b/crates/tools/sys/src/main.rs
index 1d7778ad58..2a66465c93 100644
--- a/crates/tools/sys/src/main.rs
+++ b/crates/tools/sys/src/main.rs
@@ -73,6 +73,9 @@ windows_aarch64_msvc = { path = "../../targets/aarch64_msvc", version = "0.39.0"
 [target.aarch64-uwp-windows-msvc.dependencies]
 windows_aarch64_msvc = { path = "../../targets/aarch64_msvc", version = "0.39.0" }
 
+[target.aarch64-pc-windows-gnullvm.dependencies]
+windows_aarch64_gnullvm = { path = "../../targets/aarch64_gnullvm", version = "0.39.0" }
+
 [target.i686-pc-windows-gnu.dependencies]
 windows_i686_gnu = { path = "../../targets/i686_gnu", version = "0.39.0" }
 
@@ -85,6 +88,9 @@ windows_x86_64_gnu = { path = "../../targets/x86_64_gnu", version = "0.39.0" }
 [target.x86_64-uwp-windows-gnu.dependencies]
 windows_x86_64_gnu = { path = "../../targets/x86_64_gnu", version = "0.39.0" }
 
+[target.x86_64-pc-windows-gnullvm.dependencies]
+windows_x86_64_gnullvm = { path = "../../targets/x86_64_gnullvm", version = "0.39.0" }
+
 [features]
 default = []
 deprecated = []
diff --git a/crates/tools/windows/src/main.rs b/crates/tools/windows/src/main.rs
index ab23bb4171..5f2c08c640 100644
--- a/crates/tools/windows/src/main.rs
+++ b/crates/tools/windows/src/main.rs
@@ -71,6 +71,9 @@ windows_aarch64_msvc = { path = "../../targets/aarch64_msvc", version = "0.39.0"
 [target.aarch64-uwp-windows-msvc.dependencies]
 windows_aarch64_msvc = { path = "../../targets/aarch64_msvc", version = "0.39.0" }
 
+[target.aarch64-pc-windows-gnullvm.dependencies]
+windows_aarch64_gnullvm = { path = "../../targets/aarch64_gnullvm", version = "0.39.0" }
+
 [target.i686-pc-windows-gnu.dependencies]
 windows_i686_gnu = { path = "../../targets/i686_gnu", version = "0.39.0" }
 
@@ -83,6 +86,9 @@ windows_x86_64_gnu = { path = "../../targets/x86_64_gnu", version = "0.39.0" }
 [target.x86_64-uwp-windows-gnu.dependencies]
 windows_x86_64_gnu = { path = "../../targets/x86_64_gnu", version = "0.39.0" }
 
+[target.x86_64-pc-windows-gnullvm.dependencies]
+windows_x86_64_gnullvm = { path = "../../targets/x86_64_gnullvm", version = "0.39.0" }
+
 [dependencies]
 windows-implement = { path = "../implement",  version = "0.39.0", optional = true }
 windows-interface = { path = "../interface",  version = "0.39.0", optional = true }
diff --git a/docs/publish.cmd b/docs/publish.cmd
index ac8f65acaf..82e5cea883 100644
--- a/docs/publish.cmd
+++ b/docs/publish.cmd
@@ -1,7 +1,9 @@
+cargo publish -p windows_aarch64_gnullvm
 cargo publish -p windows_aarch64_msvc
 cargo publish -p windows_i686_gnu
 cargo publish -p windows_i686_msvc
 cargo publish -p windows_x86_64_gnu
+cargo publish -p windows_x86_64_gnullvm
 cargo publish -p windows_x86_64_msvc
 cargo publish -p windows-tokens
 cargo publish -p windows-metadata