diff --git a/projects/llvm.org/mingw-w64/package.yml b/projects/llvm.org/mingw-w64/package.yml
index f5747d925c..013b37ecd8 100644
--- a/projects/llvm.org/mingw-w64/package.yml
+++ b/projects/llvm.org/mingw-w64/package.yml
@@ -1,181 +1,128 @@
-# llvm-mingw: LLVM-based mingw-w64 toolchain.
-# Cross-compiler that runs on Linux / macOS hosts and produces native
-# Windows binaries (PE/COFF) for x86-64, i686, aarch64, armv7.
+# llvm.org/mingw-w64 — from-source LLVM mingw-w64 cross-compiler toolchain.
 #
-# This is the toolchain bottle behind pkgxdev/brewkit#346 — the
-# "produce native Windows packages from Linux CI runners" RFC. Once
-# this lands, individual pantry recipes can add `platforms:
-# windows/x86-64` and depend on `llvm.org/mingw-w64` to cross-compile.
+# Builds the COMPLETE llvm-mingw toolchain from source via upstream
+# mstorsjo/llvm-mingw's own build orchestration (`build-all.sh`):
+#   - clang + lld + the LLVM binutils-equivalents
+#   - the mingw-w64 runtime (headers + CRT + winpthreads)
+#   - the LLVM runtimes for the Windows targets: compiler-rt builtins,
+#     libunwind, libc++abi, libc++
+#   - the per-target driver wrappers (install-wrappers.sh)
+# No vendored binaries — everything is compiled here.
 #
-# We re-distribute the upstream prebuilt tarballs (vendored binaries
-# from mstorsjo/llvm-mingw releases) rather than building llvm-mingw
-# from source — that'd require building LLVM itself plus the
-# mingw-w64 runtime, multi-hour and not differentiated. Upstream
-# tarballs are reproducibly-built and signed via GitHub releases.
+# Why inline (clang and all) rather than composing pantry's llvm.org: the
+# Windows-target runtimes must match the exact clang that builds them, and
+# pkgx dependency constraints can't "drift" to track that. Building the whole
+# toolchain from one source tree makes it internally consistent by
+# construction, and versioning to mstorsjo's releases (which pin the matching
+# llvm-project) means there's no LLVM-version dance to get wrong.
+#
+# Compiled on the builder at pkgx's glibc floor, so the host-side driver
+# binaries run on old hosts with NO bklibcvenv seal. (Replaces the previous
+# approach of vendoring mstorsjo's prebuilt tarball; pantry policy is
+# from-source over vendored.)
+#
+# NOTE: this is a full LLVM build — long, by design. "Build time isn't the
+# end of the world to get it right."
 
-# Source tarball is auto-generated by GitHub for each tag; the *real*
-# payload is the prebuilt-binary tarball we curl from build.script
-# (same `warnings: vendored` pattern as ziglang.org).
 distributable:
-  ~
-  # url: https://github.com/mstorsjo/llvm-mingw/archive/refs/tags/{{ version.raw }}.tar.gz
-  # strip-components: 1
+  url: https://github.com/mstorsjo/llvm-mingw/archive/refs/tags/{{version.tag}}.tar.gz
+  strip-components: 1
 
 versions:
   github: mstorsjo/llvm-mingw
 
-warnings:
-  - vendored # we redistribute upstream prebuilt binaries
-
-# Runtime libs the LLVM toolchain itself links (host-side, not the
-# Windows target). On a modern host these resolve from the system, but
-# once we bundle our own glibc (below) so the toolchain runs on old CI
-# hosts, the host's copies are bypassed — so pkgx must supply these via
-# its runtime env. These are pkgx-built, so they're guaranteed under
-# pkgx's default GLIBC_2.28 symbol floor (and are — libstdc++ 2.26, the
-# rest 2.14). It's the *vendored* upstream binaries that break that floor:
-# clang/libLLVM need GLIBC_2.34, which is the whole reason this bundle is
-# necessary. linux-only: darwin links libSystem/libc++ from the OS.
+# Runtime libs the host-side clang/lld link. Built at the 2.28 floor, so these
+# pkgx-built deps (all <= 2.28) satisfy it — pkgx supplies them via its runtime
+# env, no seal needed. linux-only (darwin links libSystem/libc++ from the OS).
 dependencies:
   linux:
     gnu.org/gcc/libstdcxx: ^14 # libstdc++.so.6 + libgcc_s.so.1
-    zlib.net: "*" # libz.so.1
-    facebook.com/zstd: "*" # libzstd.so.1
+    zlib.net: "*"
+    facebook.com/zstd: "*"
+    gnome.org/libxml2: ~2.13 # 2.14 changes the API
 
 build:
-  # We bundle our own ld.so + libc.so.6 (see the seal step) and patch the
-  # toolchain's PT_INTERP to it. brewkit's fix-patchelf would force-rpath
-  # *every* ELF under lib/ — including the bundled loader — and a loader
-  # that parses its own RPATH at startup SIGSEGVs (pkgxdev/brewkit#345,
-  # reproduced on x86-64 glibc 2.43). So skip it: the upstream binaries
-  # already carry relative $ORIGIN rpaths, bklibcvenv prepends the bundled
-  # libc dir as DT_RPATH, and cross-package deps resolve via pkgx's runtime
-  # env (same approach as the gnu.org/glibc recipe).
-  skip: fix-patchelf
   dependencies:
-    curl.se: "*"
-    gnu.org/tar: "*"
-    tukaani.org/xz: "*"
+    cmake.org: "*"
+    ninja-build.org: "*"
+    git-scm.org: "*" # build-llvm.sh / build-mingw-w64.sh clone the sources
+    python.org: "~3.11" # LLVM's build tooling
+    zlib.net: "*"
+    facebook.com/zstd: "*"
     linux:
-      # The libc to bundle. ~2.34 is the *oldest* glibc that still satisfies
-      # the vendored toolchain's symbol versions (clang/libLLVM reference up
-      # to GLIBC_2.34, above pkgx's default 2.28 floor; older won't load —
-      # see the test's glibc<2.34 guard). Bundling replaces the host libc
-      # entirely, so host range is set by glibc's --enable-kernel floor
-      # (CentOS 7), not this version.
-      gnu.org/glibc: ~2.34
+      gnu.org/gcc: ^14
+    # no compiler dep declared on purpose: brewkit's default toolchain is
+    # llvm, so the host bootstrap compiler is clang (cc/c++ shims → clang).
   env:
-    linux/x86-64:
-      PLATFORM: ubuntu-22.04-x86_64
-    linux/aarch64:
-      PLATFORM: ubuntu-22.04-aarch64
-    darwin/x86-64:
-      PLATFORM: macos-universal
-    darwin/aarch64:
-      PLATFORM: macos-universal
-    linux:
-      GLIBC_DIR: $(basename "$(echo {{deps.gnu.org/glibc.prefix}}/lib/glibc-*)")
-    URL: https://github.com/mstorsjo/llvm-mingw/releases/download/{{version.tag}}/llvm-mingw-{{version.tag}}-ucrt
-  working-directory: ${{prefix}}
+    # llvm-mingw builds per-target; we ship the x86_64 + aarch64 Windows
+    # cross-compilers (the two brewkit CI cares about).
+    TOOLCHAIN_ARCHS:
+      - x86_64
+      - aarch64
+  # mstorsjo's orchestrator builds clang/lld, native compiler-rt, installs
+  # the driver wrappers, builds the mingw-w64 runtime, then the Windows-target
+  # compiler-rt + libunwind/libc++. Trim lldb + clang-tools-extra to the
+  # cross-compiler essentials (still a full clang/lld build).
   script:
-    - curl -Lf "$URL-${PLATFORM}.tar.xz" | tar Jxpf - --strip-components=1
+    # architecture register reservation weirdness
+    - run: sed -i -f $PROP build-mingw-w64-tools.sh
+      if: linux/aarch64
+      prop: |
+        1a export CFLAGS="\${CFLAGS:-} -O2 -ffixed-x18"
 
-    # Linux: bundle our own libc + seal the toolchain so it runs on hosts
-    # whose system glibc is older than the toolchain needs (the CI-runner
-    # case behind pkgxdev/brewkit#346). darwin uses dyld/libSystem — n/a.
-    - run:
-        # The glibc dep installs its loader + libc into lib/glibc-<X.Y>/;
-        # copy that whole dir in so the bottle ships its own loader.
-        - cp -a "{{deps.gnu.org/glibc.prefix}}/lib/$GLIBC_DIR" "{{prefix}}/lib/$GLIBC_DIR"
-
-        # Force compiler-rt. After the seal moves clang to libexec/, clang's
-        # MinGW runtime auto-detection (which keys off its bin/ siblings)
-        # falls back to libgcc and emits -lgcc/-lgcc_eh, which this toolchain
-        # doesn't ship. llvm-mingw is always compiler-rt + libunwind, so make
-        # it explicit — also fixes a latent location-sensitivity bug.
-        - sed -i 's|FLAGS="$FLAGS -target $TARGET"|FLAGS="$FLAGS -rtlib=compiler-rt -unwindlib=libunwind -target $TARGET"|' bin/clang-target-wrapper.sh
-
-        # Seal: patch each toolchain binary's PT_INTERP to the bundled loader
-        # via a load-time fixup stub, keeping /proc/self/exe pointing at the
-        # real binary (so clang -> cc1 works) while staying relocatable.
-        - bklibcvenv seal "{{prefix}}" "$GLIBC_DIR"
-      if: linux
+    - ./build-all.sh "{{prefix}}"
+      --disable-lldb
+      --disable-lldb-mi
+      --disable-clang-tools-extra || (find . -name config.log -exec echo {} \; -exec cat {} \; ; false)
 
 test:
-  # winehq.org/wine is a soft dep — if present, we actually run the
-  # cross-compiled .exe through wine and verify the output. If not,
-  # we fall back to a PE magic-byte check. See pkgxdev/brewkit#346
-  # discussion: wine in pantry would let us validate the cross-compile
-  # chain end-to-end without GitHub Windows runners.
-
-  # TODO: enable after #12986 is merged
   # dependencies:
   #   winehq.org: "*"
-  env:
-    WINEDEBUG: -all
-    WINEDLLOVERRIDES: "mscoree=;mshtml="
-    WINEPREFIX: $PWD/.wine
+  # env:
+  #   WINEDEBUG: -all
+  #   WINEDLLOVERRIDES: "mscoree=;mshtml="
+  #   WINEPREFIX: $PWD/.wine
   script:
-    # Diagnostics first — surface env + filesystem state so the
-    # darwin self-hosted-runner failure (logs not externally
-    # accessible) becomes visible to maintainers.
-    - command -v aarch64-w64-mingw32-clang
-    - command -v x86_64-w64-mingw32-clang
-
-    # Cross-compile a trivial Windows binary for x86-64 and aarch64.
+    - x86_64-w64-mingw32-clang --version
     - run: cp $FIXTURE hello.c
       fixture: |
         #include <stdio.h>
-        int main(void) {
-          printf("Hello from native Windows cross-compile.\n");
-          return 0;
-        }
-    - x86_64-w64-mingw32-clang -o hello-x86_64.exe  hello.c
+        int main(void) { printf("Hello from native Windows cross-compile.\n"); return 0; }
+    - x86_64-w64-mingw32-clang  -o hello-x86_64.exe  hello.c
     - aarch64-w64-mingw32-clang -o hello-aarch64.exe hello.c
-
-    # Static signature check: PE32+ starts with "MZ" at offset 0.
-    # head -c 2 reads the raw bytes; "MZ" are printable so the shell
-    # capture works without any od/tr/sed gymnastics (which had subtle
-    # BSD-vs-GNU output-format differences and broke on darwin).
     - test "$(head -c 2 hello-x86_64.exe)" = "MZ"
     - test "$(head -c 2 hello-aarch64.exe)" = "MZ"
-
-    # Dynamic check: actually run the .exe through wine. We only run
-    # the x86-64 binary — wine on linux/aarch64 hosts can run aarch64
-    # Windows but it's flakier; static check above is enough to prove
-    # the aarch64 cross-compile worked.
-    #
-    # WINEDLLOVERRIDES disables wine's first-run Mono/Gecko prompts;
-    # WINEDEBUG silences load-time warnings. Both standard for headless.
-
-    # TODO: enable after #12986 is merged
-    - exit 0
-    - if command -v wine64 >/dev/null 2>&1; then
-    - WINE=wine64
-    - else
-    - WINE=wine
-    - fi
-
-    - test "$($WINE hello-x86_64.exe)" = "Hello from native Windows cross-compile."
-    - test "$($WINE hello-aarch64.exe)" = "Hello from native Windows cross-compile."
+    - if ! command -v wine64 >/dev/null 2>&1; then exit 0; fi
+    - test "$(wine64 hello-x86_64.exe | tr -d '\r')" = "Hello from native Windows cross-compile."
 
 provides:
-  # x86_64 cross drivers
   - bin/x86_64-w64-mingw32-clang
   - bin/x86_64-w64-mingw32-clang++
   - bin/x86_64-w64-mingw32-gcc
   - bin/x86_64-w64-mingw32-g++
-  # aarch64 cross drivers
+  - bin/x86_64-w64-mingw32-ar
+  - bin/x86_64-w64-mingw32-ranlib
+  - bin/x86_64-w64-mingw32-strip
+  - bin/x86_64-w64-mingw32-nm
+  - bin/x86_64-w64-mingw32-objdump
+  - bin/x86_64-w64-mingw32-objcopy
+  - bin/x86_64-w64-mingw32-windres
+  - bin/x86_64-w64-mingw32-dlltool
   - bin/aarch64-w64-mingw32-clang
   - bin/aarch64-w64-mingw32-clang++
   - bin/aarch64-w64-mingw32-gcc
   - bin/aarch64-w64-mingw32-g++
-  # i686 cross drivers
-  - bin/i686-w64-mingw32-clang
-  - bin/i686-w64-mingw32-clang++
-  # PE-aware tooling (analog of binutils for ELF). llvm-mt isn't
-  # shipped as a separate binary in current llvm-mingw builds —
-  # rc/cvtres cover the manifest+resource pipeline.
-  - bin/llvm-rc # resource compiler (rc.exe)
-  - bin/llvm-cvtres # COFF tooling
-  - bin/lld-link # MSVC-compat linker (link.exe)
+  - bin/aarch64-w64-mingw32-ar
+  - bin/aarch64-w64-mingw32-ranlib
+  - bin/aarch64-w64-mingw32-strip
+  - bin/aarch64-w64-mingw32-nm
+  - bin/aarch64-w64-mingw32-objdump
+  - bin/aarch64-w64-mingw32-objcopy
+  - bin/aarch64-w64-mingw32-windres
+  - bin/aarch64-w64-mingw32-dlltool
+  # don't want to grab these.
+  # - bin/clang
+  # - bin/clang++
+  - bin/lld-link
+  - bin/llvm-rc
+  - bin/llvm-cvtres