diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index ad67596360bc..4077526879b6 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -1,97 +1,215 @@
 name: ci
 on:
-  pull_request:
   push:
     branches:
-      - master
-concurrency:
-  # Cancels pending runs when a PR gets updated.
-  group: ${{ github.head_ref || github.run_id }}-${{ github.actor }}
-  cancel-in-progress: true
+      - ci-scripts
+env:
+  ci-zig-version: 0.13.0-dev.76+dee9f82f6
 jobs:
   x86_64-linux-debug:
-    timeout-minutes: 420
+    if: github.repository_owner == 'ziglang'
     runs-on: [self-hosted, Linux, x86_64]
     steps:
+      - name: Download Zig
+        run: 'mkdir -p ~/deps && ! mkdir ~/deps/zig-x86_64-linux-musl-${{env.ci-zig-version}} 2> /dev/null || curl https://jacobly.com/deps/zig-x86_64-linux-musl-${{env.ci-zig-version}}.tar.xz | tar xJ -C ~/deps'
       - name: Checkout
         uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
       - name: Build and Test
-        run: sh ci/x86_64-linux-debug.sh
+        working-directory: ci
+        run: ~/deps/zig-x86_64-linux-musl-${{env.ci-zig-version}}/bin/zig build --maxrss 21000000000 -Dbuild-type=Debug -Dextra-target=arm-linux-musleabihf cmake-bootstrap tidy update-stage1
   x86_64-linux-release:
-    timeout-minutes: 420
+    if: github.repository_owner == 'ziglang'
     runs-on: [self-hosted, Linux, x86_64]
     steps:
+      - name: Download Zig
+        run: 'mkdir -p ~/deps && ! mkdir ~/deps/zig-x86_64-linux-musl-${{env.ci-zig-version}} 2> /dev/null || curl https://jacobly.com/deps/zig-x86_64-linux-musl-${{env.ci-zig-version}}.tar.xz | tar xJ -C ~/deps'
       - name: Checkout
         uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
       - name: Build and Test
-        run: sh ci/x86_64-linux-release.sh
+        working-directory: ci
+        run: ~/deps/zig-x86_64-linux-musl-${{env.ci-zig-version}}/bin/zig build --maxrss 21000000000 -Dbuild-type=Release -Dextra-target=arm-linux-musleabihf -Dcc=cc cc-bootstrap cmake-bootstrap tidy reproducible update-stage1
   aarch64-linux-debug:
-    timeout-minutes: 480
+    if: github.repository_owner == 'ziglang'
     runs-on: [self-hosted, Linux, aarch64]
     steps:
+      - name: Download Zig
+        run: 'mkdir -p ~/deps && ! mkdir ~/deps/zig-aarch64-linux-musl-${{env.ci-zig-version}} 2> /dev/null || curl https://jacobly.com/deps/zig-aarch64-linux-musl-${{env.ci-zig-version}}.tar.xz | tar xJ -C ~/deps'
       - name: Checkout
         uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
       - name: Build and Test
-        run: sh ci/aarch64-linux-debug.sh
+        working-directory: ci
+        run: ~/deps/zig-aarch64-linux-musl-${{env.ci-zig-version}}/bin/zig build --maxrss 24696061952 -Dbuild-type=Debug -Dextra-target=arm-linux-musleabihf cmake-bootstrap tidy update-stage1
   aarch64-linux-release:
-    timeout-minutes: 480
+    if: github.repository_owner == 'ziglang'
     runs-on: [self-hosted, Linux, aarch64]
     steps:
+      - name: Download Zig
+        run: 'mkdir -p ~/deps && ! mkdir ~/deps/zig-aarch64-linux-musl-${{env.ci-zig-version}} 2> /dev/null || curl https://jacobly.com/deps/zig-aarch64-linux-musl-${{env.ci-zig-version}}.tar.xz | tar xJ -C ~/deps'
       - name: Checkout
         uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
       - name: Build and Test
-        run: sh ci/aarch64-linux-release.sh
+        working-directory: ci
+        run: ~/deps/zig-aarch64-linux-musl-${{env.ci-zig-version}}/bin/zig build --maxrss 24696061952 -Dbuild-type=Release -Dextra-target=arm-linux-musleabihf cmake-bootstrap tidy reproducible update-stage1
+  x86_64-macos-debug:
+    if: github.repository_owner == 'ziglang'
+    runs-on: "macos-11"
+    steps:
+      - name: Restore Zig Cache
+        id: zig-cache
+        uses: actions/cache/restore@v4
+        with:
+          path: ~/deps/zig-x86_64-macos-none-${{env.ci-zig-version}}
+          key: zig-x86_64-macos-none-${{env.ci-zig-version}}
+      - name: Download Zig
+        if: steps.zig-cache.outputs.cache-hit != 'true'
+        run: 'mkdir -p ~/deps && curl https://jacobly.com/deps/zig-x86_64-macos-none-${{env.ci-zig-version}}.tar.xz | tar xJ -C ~/deps'
+      - name: Save Zig Cache
+        if: steps.zig-cache.outputs.cache-hit != 'true'
+        uses: actions/cache/save@v4
+        with:
+          path: ~/deps/zig-x86_64-macos-none-${{env.ci-zig-version}}
+          key: ${{steps.zig-cache.outputs.cache-primary-key}}
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+      - name: Restore Package Cache
+        id: package-cache
+        uses: actions/cache/restore@v4
+        with:
+          path: ~/.cache/zig
+          key: x86_64-macos-package-${{hashFiles('ci/build.zig.zon')}}
+          restore-keys: x86_64-macos-package-
+      - name: Build and Test
+        working-directory: ci
+        run: ~/deps/zig-x86_64-macos-none-${{env.ci-zig-version}}/bin/zig build -Dbuild-type=Debug -Dskip-non-native cmake-bootstrap tidy update-stage1
+      - name: Save Package Cache
+        if: steps.package-cache.outputs.cache-hit != 'true'
+        uses: actions/cache/save@v4
+        with:
+          path: ~/.cache/zig
+          key: ${{steps.package-cache.outputs.cache-primary-key}}
   x86_64-macos-release:
+    if: github.repository_owner == 'ziglang'
     runs-on: "macos-11"
-    env:
-      ARCH: "x86_64"
     steps:
+      - name: Restore Zig Cache
+        id: zig-cache
+        uses: actions/cache/restore@v4
+        with:
+          path: ~/deps/zig-x86_64-macos-none-${{env.ci-zig-version}}
+          key: zig-x86_64-macos-none-${{env.ci-zig-version}}
+      - name: Download Zig
+        if: steps.zig-cache.outputs.cache-hit != 'true'
+        run: 'mkdir -p ~/deps && curl https://jacobly.com/deps/zig-x86_64-macos-none-${{env.ci-zig-version}}.tar.xz | tar xJ -C ~/deps'
+      - name: Save Zig Cache
+        if: steps.zig-cache.outputs.cache-hit != 'true'
+        uses: actions/cache/save@v4
+        with:
+          path: ~/deps/zig-x86_64-macos-none-${{env.ci-zig-version}}
+          key: ${{steps.zig-cache.outputs.cache-primary-key}}
       - name: Checkout
         uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+      - name: Restore Package Cache
+        id: package-cache
+        uses: actions/cache/restore@v4
+        with:
+          path: ~/.cache/zig
+          key: x86_64-macos-package-${{hashFiles('ci/build.zig.zon')}}
+          restore-keys: x86_64-macos-package-
       - name: Build and Test
-        run: ci/x86_64-macos-release.sh
+        working-directory: ci
+        run: ~/deps/zig-x86_64-macos-none-${{env.ci-zig-version}}/bin/zig build -Dbuild-type=Release -Dcc=cc -Dskip-non-native cc-bootstrap cmake-bootstrap tidy reproducible update-stage1
+      - name: Save Package Cache
+        if: steps.package-cache.outputs.cache-hit != 'true'
+        uses: actions/cache/save@v4
+        with:
+          path: ~/.cache/zig
+          key: ${{steps.package-cache.outputs.cache-primary-key}}
   aarch64-macos-debug:
+    if: github.repository_owner == 'ziglang'
     runs-on: [self-hosted, macOS, aarch64]
-    env:
-      ARCH: "aarch64"
     steps:
+      - name: Download Zig
+        run: 'mkdir -p ~/deps && ! mkdir ~/deps/zig-aarch64-macos-none-${{env.ci-zig-version}} 2> /dev/null || curl https://jacobly.com/deps/zig-aarch64-macos-none-${{env.ci-zig-version}}.tar.xz | tar xJ -C ~/deps'
       - name: Checkout
         uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
       - name: Build and Test
-        run: ci/aarch64-macos-debug.sh
+        working-directory: ci
+        run: ~/deps/zig-aarch64-macos-none-${{env.ci-zig-version}}/bin/zig build -Dbuild-type=Debug -Dskip-non-native cmake-bootstrap tidy update-stage1
   aarch64-macos-release:
+    if: github.repository_owner == 'ziglang'
     runs-on: [self-hosted, macOS, aarch64]
-    env:
-      ARCH: "aarch64"
     steps:
+      - name: Download Zig
+        run: 'mkdir -p ~/deps && ! mkdir ~/deps/zig-aarch64-macos-none-${{env.ci-zig-version}} 2> /dev/null || curl https://jacobly.com/deps/zig-aarch64-macos-none-${{env.ci-zig-version}}.tar.xz | tar xJ -C ~/deps'
       - name: Checkout
         uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
       - name: Build and Test
-        run: ci/aarch64-macos-release.sh
+        working-directory: ci
+        run: ~/deps/zig-aarch64-macos-none-${{env.ci-zig-version}}/bin/zig build -Dbuild-type=Release -Dskip-non-native cmake-bootstrap tidy reproducible update-stage1
   x86_64-windows-debug:
+    if: github.repository_owner == 'ziglang'
     runs-on: [self-hosted, Windows, x86_64]
-    env:
-      ARCH: "x86_64"
     steps:
+      - name: Download Zig
+        run: |
+          if (New-Item -Path $Env:USERPROFILE\deps\zig-x86_64-windows-gnu-${{env.ci-zig-version}} -ItemType Directory -ErrorAction Ignore) {
+            Invoke-WebRequest -Uri https://jacobly.com/deps/zig-x86_64-windows-gnu-${{env.ci-zig-version}}.zip -OutFile zig-x86_64-windows-gnu-${{env.ci-zig-version}}.zip
+            Expand-Archive -LiteralPath zig-x86_64-windows-gnu-${{env.ci-zig-version}}.zip -DestinationPath $Env:USERPROFILE\deps
+          }
       - name: Checkout
         uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
       - name: Build and Test
-        run: ci/x86_64-windows-debug.ps1
+        working-directory: ci
+        run: '& $Env:USERPROFILE\deps\zig-x86_64-windows-gnu-${{env.ci-zig-version}}\bin\zig.exe build -Dbuild-type=Debug -Dskip-non-native cmake-bootstrap tidy update-stage1 msvc'
   x86_64-windows-release:
+    if: github.repository_owner == 'ziglang'
     runs-on: [self-hosted, Windows, x86_64]
-    env:
-      ARCH: "x86_64"
     steps:
+      - name: Download Zig
+        run: |
+          if (New-Item -Path $Env:USERPROFILE\deps\zig-x86_64-windows-gnu-${{env.ci-zig-version}} -ItemType Directory -ErrorAction Ignore) {
+            Invoke-WebRequest -Uri https://jacobly.com/deps/zig-x86_64-windows-gnu-${{env.ci-zig-version}}.zip -OutFile zig-x86_64-windows-gnu-${{env.ci-zig-version}}.zip
+            Expand-Archive -LiteralPath zig-x86_64-windows-gnu-${{env.ci-zig-version}}.zip -DestinationPath $Env:USERPROFILE\deps
+          }
       - name: Checkout
         uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
       - name: Build and Test
-        run: ci/x86_64-windows-release.ps1
-  aarch64-windows:
+        working-directory: ci
+        run: '& $Env:USERPROFILE\deps\zig-x86_64-windows-gnu-${{env.ci-zig-version}}\bin\zig.exe build -Dbuild-type=Release -Dskip-non-native cmake-bootstrap tidy update-stage1 msvc' # reproducible
+  aarch64-windows-release:
+    if: github.repository_owner == 'ziglang'
     runs-on: [self-hosted, Windows, aarch64]
-    env:
-      ARCH: "aarch64"
     steps:
+      - name: Download Zig
+        run: |
+          if (New-Item -Path $Env:USERPROFILE\deps\zig-aarch64-windows-gnu-${{env.ci-zig-version}} -ItemType Directory -ErrorAction Ignore) {
+            Invoke-WebRequest -Uri https://jacobly.com/deps/zig-aarch64-windows-gnu-${{env.ci-zig-version}}.zip -OutFile zig-aarch64-windows-gnu-${{env.ci-zig-version}}.zip
+            Expand-Archive -LiteralPath zig-aarch64-windows-gnu-${{env.ci-zig-version}}.zip -DestinationPath $Env:USERPROFILE\deps
+          }
       - name: Checkout
         uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
       - name: Build and Test
-        run: ci/aarch64-windows.ps1
+        working-directory: ci
+        run: '& $Env:USERPROFILE\deps\zig-aarch64-windows-gnu-${{env.ci-zig-version}}\bin\zig.exe build -Dbuild-type=Release -Dskip-non-native cmake-bootstrap tidy' # reproducible
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 718e89c7cbb5..aacc5d461375 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -681,7 +681,7 @@ include_directories(
 if(MSVC)
   set(EXE_CXX_FLAGS "/std:c++17")
   set(EXE_LDFLAGS "/STACK:16777216")
-  if(NOT "${CMAKE_BUILD_TYPE}" STREQUAL "Release" AND NOT "${CMAKE_BUILD_TYPE}" STREQUAL "MinSizeRel")
+  if(NOT "${CMAKE_BUILD_TYPE}" STREQUAL "Release")
     set(EXE_LDFLAGS "${EXE_LDFLAGS} /debug:fastlink")
   endif()
 else()
@@ -885,10 +885,12 @@ endif()
 
 if("${CMAKE_BUILD_TYPE}" STREQUAL "Debug")
   set(ZIG_RELEASE_ARG "")
+elseif("${CMAKE_BUILD_TYPE}" STREQUAL "Release")
+  set(ZIG_RELEASE_ARG -Doptimize=ReleaseFast -Dstrip)
 elseif("${CMAKE_BUILD_TYPE}" STREQUAL "RelWithDebInfo")
   set(ZIG_RELEASE_ARG -Doptimize=ReleaseFast)
-else()
-  set(ZIG_RELEASE_ARG -Doptimize=ReleaseFast -Dstrip)
+elseif("${CMAKE_BUILD_TYPE}" STREQUAL "MinSizeRel")
+  set(ZIG_RELEASE_ARG -Doptimize=ReleaseSmall)
 endif()
 if(ZIG_NO_LIB)
   set(ZIG_NO_LIB_ARG "-Dno-lib")
diff --git a/build.zig b/build.zig
index f5af65c7b5c4..adce95a8d337 100644
--- a/build.zig
+++ b/build.zig
@@ -426,7 +426,7 @@ pub fn build(b: *std.Build) !void {
     const optimization_modes = chosen_opt_modes_buf[0..chosen_mode_index];
 
     const fmt_include_paths = &.{ "doc", "lib", "src", "test", "tools", "build.zig" };
-    const fmt_exclude_paths = &.{"test/cases"};
+    const fmt_exclude_paths = &.{ "doc/langref", "test/cases" };
     const do_fmt = b.addFmt(.{
         .paths = fmt_include_paths,
         .exclude_paths = fmt_exclude_paths,
diff --git a/ci/aarch64-linux-debug.sh b/ci/aarch64-linux-debug.sh
deleted file mode 100644
index b75911fa5601..000000000000
--- a/ci/aarch64-linux-debug.sh
+++ /dev/null
@@ -1,110 +0,0 @@
-#!/bin/sh
-
-# Requires cmake ninja-build
-
-set -x
-set -e
-
-ARCH="$(uname -m)"
-TARGET="$ARCH-linux-musl"
-MCPU="baseline"
-CACHE_BASENAME="zig+llvm+lld+clang-$TARGET-0.12.0-dev.203+d3bc1cfc4"
-PREFIX="$HOME/deps/$CACHE_BASENAME"
-ZIG="$PREFIX/bin/zig"
-
-export PATH="$HOME/deps/wasmtime-v10.0.2-$ARCH-linux:$PATH"
-
-# Make the `zig version` number consistent.
-# This will affect the cmake command below.
-git fetch --unshallow || true
-git fetch --tags
-
-export CC="$ZIG cc -target $TARGET -mcpu=$MCPU"
-export CXX="$ZIG c++ -target $TARGET -mcpu=$MCPU"
-
-rm -rf build-debug
-mkdir build-debug
-cd build-debug
-
-# Override the cache directories because they won't actually help other CI runs
-# which will be testing alternate versions of zig, and ultimately would just
-# fill up space on the hard drive for no reason.
-export ZIG_GLOBAL_CACHE_DIR="$PWD/zig-global-cache"
-export ZIG_LOCAL_CACHE_DIR="$PWD/zig-local-cache"
-
-cmake .. \
-  -DCMAKE_INSTALL_PREFIX="stage3-debug" \
-  -DCMAKE_PREFIX_PATH="$PREFIX" \
-  -DCMAKE_BUILD_TYPE=Debug \
-  -DZIG_TARGET_TRIPLE="$TARGET" \
-  -DZIG_TARGET_MCPU="$MCPU" \
-  -DZIG_STATIC=ON \
-  -DZIG_NO_LIB=ON \
-  -GNinja
-
-# Now cmake will use zig as the C/C++ compiler. We reset the environment variables
-# so that installation and testing do not get affected by them.
-unset CC
-unset CXX
-
-ninja install
-
-# TODO: move this to a build.zig step (check-fmt)
-echo "Looking for non-conforming code formatting..."
-stage3-debug/bin/zig fmt --check .. \
-  --exclude ../test/cases/ \
-  --exclude ../doc/ \
-  --exclude ../build-debug
-
-# simultaneously test building self-hosted without LLVM and with 32-bit arm
-stage3-debug/bin/zig build \
-  -Dtarget=arm-linux-musleabihf \
-  -Dno-lib
-
-# TODO: add -fqemu back to this line
-stage3-debug/bin/zig build test docs \
-  --maxrss 24696061952 \
-  -fwasmtime \
-  -Dstatic-llvm \
-  -Dtarget=native-native-musl \
-  --search-prefix "$PREFIX" \
-  --zig-lib-dir "$PWD/../lib"
-
-# Look for HTML errors.
-# TODO: move this to a build.zig flag (-Denable-tidy)
-tidy --drop-empty-elements no -qe "../zig-out/doc/langref.html"
-
-# Ensure that updating the wasm binary from this commit will result in a viable build.
-stage3-debug/bin/zig build update-zig1
-
-rm -rf ../build-new
-mkdir ../build-new
-cd ../build-new
-
-export ZIG_GLOBAL_CACHE_DIR="$PWD/zig-global-cache"
-export ZIG_LOCAL_CACHE_DIR="$PWD/zig-local-cache"
-export CC="$ZIG cc -target $TARGET -mcpu=$MCPU"
-export CXX="$ZIG c++ -target $TARGET -mcpu=$MCPU"
-
-cmake .. \
-  -DCMAKE_PREFIX_PATH="$PREFIX" \
-  -DCMAKE_BUILD_TYPE=Debug \
-  -DZIG_TARGET_TRIPLE="$TARGET" \
-  -DZIG_TARGET_MCPU="$MCPU" \
-  -DZIG_STATIC=ON \
-  -DZIG_NO_LIB=ON \
-  -GNinja
-
-unset CC
-unset CXX
-
-ninja install
-
-stage3/bin/zig test ../test/behavior.zig
-stage3/bin/zig build -p stage4 \
-  -Dstatic-llvm \
-  -Dtarget=native-native-musl \
-  -Dno-lib \
-  --search-prefix "$PREFIX" \
-  --zig-lib-dir "$PWD/../lib"
-stage4/bin/zig test ../test/behavior.zig
diff --git a/ci/aarch64-linux-release.sh b/ci/aarch64-linux-release.sh
deleted file mode 100644
index a43f162eb59d..000000000000
--- a/ci/aarch64-linux-release.sh
+++ /dev/null
@@ -1,110 +0,0 @@
-#!/bin/sh
-
-# Requires cmake ninja-build
-
-set -x
-set -e
-
-ARCH="$(uname -m)"
-TARGET="$ARCH-linux-musl"
-MCPU="baseline"
-CACHE_BASENAME="zig+llvm+lld+clang-$TARGET-0.12.0-dev.203+d3bc1cfc4"
-PREFIX="$HOME/deps/$CACHE_BASENAME"
-ZIG="$PREFIX/bin/zig"
-
-export PATH="$HOME/deps/wasmtime-v10.0.2-$ARCH-linux:$PATH"
-
-# Make the `zig version` number consistent.
-# This will affect the cmake command below.
-git fetch --unshallow || true
-git fetch --tags
-
-export CC="$ZIG cc -target $TARGET -mcpu=$MCPU"
-export CXX="$ZIG c++ -target $TARGET -mcpu=$MCPU"
-
-rm -rf build-release
-mkdir build-release
-cd build-release
-
-# Override the cache directories because they won't actually help other CI runs
-# which will be testing alternate versions of zig, and ultimately would just
-# fill up space on the hard drive for no reason.
-export ZIG_GLOBAL_CACHE_DIR="$PWD/zig-global-cache"
-export ZIG_LOCAL_CACHE_DIR="$PWD/zig-local-cache"
-
-cmake .. \
-  -DCMAKE_INSTALL_PREFIX="stage3-release" \
-  -DCMAKE_PREFIX_PATH="$PREFIX" \
-  -DCMAKE_BUILD_TYPE=Release \
-  -DZIG_TARGET_TRIPLE="$TARGET" \
-  -DZIG_TARGET_MCPU="$MCPU" \
-  -DZIG_STATIC=ON \
-  -DZIG_NO_LIB=ON \
-  -GNinja
-
-# Now cmake will use zig as the C/C++ compiler. We reset the environment variables
-# so that installation and testing do not get affected by them.
-unset CC
-unset CXX
-
-ninja install
-
-# TODO: move this to a build.zig step (check-fmt)
-echo "Looking for non-conforming code formatting..."
-stage3-release/bin/zig fmt --check .. \
-  --exclude ../test/cases/ \
-  --exclude ../doc/ \
-  --exclude ../build-release
-
-# simultaneously test building self-hosted without LLVM and with 32-bit arm
-stage3-release/bin/zig build \
-  -Dtarget=arm-linux-musleabihf \
-  -Dno-lib
-
-# TODO: add -fqemu back to this line
-stage3-release/bin/zig build test docs \
-  --maxrss 24696061952 \
-  -fwasmtime \
-  -Dstatic-llvm \
-  -Dtarget=native-native-musl \
-  --search-prefix "$PREFIX" \
-  --zig-lib-dir "$PWD/../lib"
-
-# Look for HTML errors.
-# TODO: move this to a build.zig flag (-Denable-tidy)
-tidy --drop-empty-elements no -qe "../zig-out/doc/langref.html"
-
-# Ensure that updating the wasm binary from this commit will result in a viable build.
-stage3-release/bin/zig build update-zig1
-
-rm -rf ../build-new
-mkdir ../build-new
-cd ../build-new
-
-export ZIG_GLOBAL_CACHE_DIR="$PWD/zig-global-cache"
-export ZIG_LOCAL_CACHE_DIR="$PWD/zig-local-cache"
-export CC="$ZIG cc -target $TARGET -mcpu=$MCPU"
-export CXX="$ZIG c++ -target $TARGET -mcpu=$MCPU"
-
-cmake .. \
-  -DCMAKE_PREFIX_PATH="$PREFIX" \
-  -DCMAKE_BUILD_TYPE=Release \
-  -DZIG_TARGET_TRIPLE="$TARGET" \
-  -DZIG_TARGET_MCPU="$MCPU" \
-  -DZIG_STATIC=ON \
-  -DZIG_NO_LIB=ON \
-  -GNinja
-
-unset CC
-unset CXX
-
-ninja install
-
-stage3/bin/zig test ../test/behavior.zig
-stage3/bin/zig build -p stage4 \
-  -Dstatic-llvm \
-  -Dtarget=native-native-musl \
-  -Dno-lib \
-  --search-prefix "$PREFIX" \
-  --zig-lib-dir "$PWD/../lib"
-stage4/bin/zig test ../test/behavior.zig
diff --git a/ci/aarch64-macos-debug.sh b/ci/aarch64-macos-debug.sh
deleted file mode 100755
index fb85914c491c..000000000000
--- a/ci/aarch64-macos-debug.sh
+++ /dev/null
@@ -1,51 +0,0 @@
-#!/bin/sh
-
-set -x
-set -e
-
-# Script assumes the presence of the following:
-# s3cmd
-
-ZIGDIR="$PWD"
-TARGET="$ARCH-macos-none"
-MCPU="baseline"
-CACHE_BASENAME="zig+llvm+lld+clang-$TARGET-0.12.0-dev.467+0345d7866"
-PREFIX="$HOME/$CACHE_BASENAME"
-ZIG="$PREFIX/bin/zig"
-
-cd $ZIGDIR
-
-# Make the `zig version` number consistent.
-# This will affect the cmake command below.
-git fetch --unshallow || true
-git fetch --tags
-
-mkdir build
-cd build
-
-# Override the cache directories because they won't actually help other CI runs
-# which will be testing alternate versions of zig, and ultimately would just
-# fill up space on the hard drive for no reason.
-export ZIG_GLOBAL_CACHE_DIR="$PWD/zig-global-cache"
-export ZIG_LOCAL_CACHE_DIR="$PWD/zig-local-cache"
-
-PATH="$HOME/local/bin:$PATH" cmake .. \
-  -DCMAKE_INSTALL_PREFIX="stage3-debug" \
-  -DCMAKE_PREFIX_PATH="$PREFIX" \
-  -DCMAKE_BUILD_TYPE=Debug \
-  -DCMAKE_C_COMPILER="$ZIG;cc;-target;$TARGET;-mcpu=$MCPU" \
-  -DCMAKE_CXX_COMPILER="$ZIG;c++;-target;$TARGET;-mcpu=$MCPU" \
-  -DZIG_TARGET_TRIPLE="$TARGET" \
-  -DZIG_TARGET_MCPU="$MCPU" \
-  -DZIG_STATIC=ON \
-  -DZIG_NO_LIB=ON \
-  -GNinja
-
-$HOME/local/bin/ninja install
-
-stage3-debug/bin/zig build test docs \
-  --zig-lib-dir "$PWD/../lib" \
-  -Denable-macos-sdk \
-  -Dstatic-llvm \
-  -Dskip-non-native \
-  --search-prefix "$PREFIX"
diff --git a/ci/aarch64-macos-release.sh b/ci/aarch64-macos-release.sh
deleted file mode 100755
index e34c3e31daca..000000000000
--- a/ci/aarch64-macos-release.sh
+++ /dev/null
@@ -1,67 +0,0 @@
-#!/bin/sh
-
-set -x
-set -e
-
-# Script assumes the presence of the following:
-# s3cmd
-
-ZIGDIR="$PWD"
-TARGET="$ARCH-macos-none"
-MCPU="baseline"
-CACHE_BASENAME="zig+llvm+lld+clang-$TARGET-0.12.0-dev.467+0345d7866"
-PREFIX="$HOME/$CACHE_BASENAME"
-ZIG="$PREFIX/bin/zig"
-
-cd $ZIGDIR
-
-# Make the `zig version` number consistent.
-# This will affect the cmake command below.
-git fetch --unshallow || true
-git fetch --tags
-
-mkdir build
-cd build
-
-# Override the cache directories because they won't actually help other CI runs
-# which will be testing alternate versions of zig, and ultimately would just
-# fill up space on the hard drive for no reason.
-export ZIG_GLOBAL_CACHE_DIR="$PWD/zig-global-cache"
-export ZIG_LOCAL_CACHE_DIR="$PWD/zig-local-cache"
-
-PATH="$HOME/local/bin:$PATH" cmake .. \
-  -DCMAKE_INSTALL_PREFIX="stage3-release" \
-  -DCMAKE_PREFIX_PATH="$PREFIX" \
-  -DCMAKE_BUILD_TYPE=Release \
-  -DCMAKE_C_COMPILER="$ZIG;cc;-target;$TARGET;-mcpu=$MCPU" \
-  -DCMAKE_CXX_COMPILER="$ZIG;c++;-target;$TARGET;-mcpu=$MCPU" \
-  -DZIG_TARGET_TRIPLE="$TARGET" \
-  -DZIG_TARGET_MCPU="$MCPU" \
-  -DZIG_STATIC=ON \
-  -DZIG_NO_LIB=ON \
-  -GNinja
-
-$HOME/local/bin/ninja install
-
-stage3-release/bin/zig build test docs \
-  --zig-lib-dir "$PWD/../lib" \
-  -Denable-macos-sdk \
-  -Dstatic-llvm \
-  -Dskip-non-native \
-  --search-prefix "$PREFIX"
-
-# Ensure that stage3 and stage4 are byte-for-byte identical.
-stage3-release/bin/zig build \
-  --prefix stage4-release \
-  -Denable-llvm \
-  -Dno-lib \
-  -Doptimize=ReleaseFast \
-  -Dstrip \
-  -Dtarget=$TARGET \
-  -Duse-zig-libcxx \
-  -Dversion-string="$(stage3-release/bin/zig version)"
-
-# diff returns an error code if the files differ.
-echo "If the following command fails, it means nondeterminism has been"
-echo "introduced, making stage3 and stage4 no longer byte-for-byte identical."
-diff stage3-release/bin/zig stage4-release/bin/zig
diff --git a/ci/aarch64-windows.ps1 b/ci/aarch64-windows.ps1
deleted file mode 100644
index 72da7c3a89d6..000000000000
--- a/ci/aarch64-windows.ps1
+++ /dev/null
@@ -1,71 +0,0 @@
-$TARGET = "$($Env:ARCH)-windows-gnu"
-$ZIG_LLVM_CLANG_LLD_NAME = "zig+llvm+lld+clang-$TARGET-0.12.0-dev.2087+e9a18010b"
-$MCPU = "baseline"
-$ZIG_LLVM_CLANG_LLD_URL = "https://ziglang.org/deps/$ZIG_LLVM_CLANG_LLD_NAME.zip"
-$PREFIX_PATH = "$(Get-Location)\..\$ZIG_LLVM_CLANG_LLD_NAME"
-$ZIG = "$PREFIX_PATH\bin\zig.exe"
-$ZIG_LIB_DIR = "$(Get-Location)\lib"
-
-if (!(Test-Path "..\$ZIG_LLVM_CLANG_LLD_NAME.zip")) {
-    Write-Output "Downloading $ZIG_LLVM_CLANG_LLD_URL"
-    Invoke-WebRequest -Uri "$ZIG_LLVM_CLANG_LLD_URL" -OutFile "..\$ZIG_LLVM_CLANG_LLD_NAME.zip"
-
-    Write-Output "Extracting..."
-    Add-Type -AssemblyName System.IO.Compression.FileSystem ;
-    [System.IO.Compression.ZipFile]::ExtractToDirectory("$PWD\..\$ZIG_LLVM_CLANG_LLD_NAME.zip", "$PWD\..")
-}
-
-function CheckLastExitCode {
-    if (!$?) {
-        exit 1
-    }
-    return 0
-}
-
-# Make the `zig version` number consistent.
-# This will affect the `zig build` command below which uses `git describe`.
-git fetch --tags
-
-if ((git rev-parse --is-shallow-repository) -eq "true") {
-    git fetch --unshallow # `git describe` won't work on a shallow repo
-}
-
-Write-Output "Building from source..."
-Remove-Item -Path 'build-release' -Recurse -Force -ErrorAction Ignore
-New-Item -Path 'build-release' -ItemType Directory
-Set-Location -Path 'build-release'
-
-# Override the cache directories because they won't actually help other CI runs
-# which will be testing alternate versions of zig, and ultimately would just
-# fill up space on the hard drive for no reason.
-$Env:ZIG_GLOBAL_CACHE_DIR="$(Get-Location)\zig-global-cache"
-$Env:ZIG_LOCAL_CACHE_DIR="$(Get-Location)\zig-local-cache"
-
-# CMake gives a syntax error when file paths with backward slashes are used.
-# Here, we use forward slashes only to work around this.
-& cmake .. `
-  -GNinja `
-  -DCMAKE_INSTALL_PREFIX="stage3-release" `
-  -DCMAKE_PREFIX_PATH="$($PREFIX_PATH -Replace "\\", "/")" `
-  -DCMAKE_BUILD_TYPE=Release `
-  -DCMAKE_C_COMPILER="$($ZIG -Replace "\\", "/");cc;-target;$TARGET;-mcpu=$MCPU" `
-  -DCMAKE_CXX_COMPILER="$($ZIG -Replace "\\", "/");c++;-target;$TARGET;-mcpu=$MCPU" `
-  -DCMAKE_AR="$ZIG" `
-  -DZIG_AR_WORKAROUND=ON `
-  -DZIG_TARGET_TRIPLE="$TARGET" `
-  -DZIG_TARGET_MCPU="$MCPU" `
-  -DZIG_STATIC=ON `
-  -DZIG_NO_LIB=ON
-CheckLastExitCode
-
-ninja install
-CheckLastExitCode
-
-Write-Output "Main test suite..."
-& "stage3-release\bin\zig.exe" build test docs `
-  --zig-lib-dir "$ZIG_LIB_DIR" `
-  --search-prefix "$PREFIX_PATH" `
-  -Dstatic-llvm `
-  -Dskip-non-native `
-  -Denable-symlinks-windows
-CheckLastExitCode
diff --git a/ci/build.zig b/ci/build.zig
new file mode 100644
index 000000000000..e21eab86b663
--- /dev/null
+++ b/ci/build.zig
@@ -0,0 +1,666 @@
+const std = @import("std");
+
+pub fn build(b: *std.Build) void {
+    const host_target = b.standardTargetOptions(.{
+        .whitelist = &.{
+            .{
+                .cpu_arch = .x86_64,
+                .cpu_model = .baseline,
+                .os_tag = .linux,
+                .abi = .musl,
+            },
+            .{
+                .cpu_arch = .aarch64,
+                .cpu_model = .baseline,
+                .os_tag = .linux,
+                .abi = .musl,
+            },
+            .{
+                .cpu_arch = .x86_64,
+                .cpu_model = .baseline,
+                .os_tag = .macos,
+                .abi = .none,
+            },
+            .{
+                .cpu_arch = .aarch64,
+                .cpu_model = .baseline,
+                .os_tag = .macos,
+                .abi = .none,
+            },
+            .{
+                .cpu_arch = .x86_64,
+                .cpu_model = .baseline,
+                .os_tag = .windows,
+                .abi = .gnu,
+            },
+            .{
+                .cpu_arch = .aarch64,
+                .cpu_model = .baseline,
+                .os_tag = .windows,
+                .abi = .gnu,
+            },
+        },
+        .default_target = .{
+            .cpu_arch = b.graph.host.result.cpu.arch,
+            .cpu_model = .baseline,
+            .os_tag = b.graph.host.result.os.tag,
+            .abi = if (b.graph.host.result.os.tag == .windows)
+                .gnu
+            else if (b.graph.host.result.isDarwin())
+                .none
+            else
+                .musl,
+        },
+    });
+    const host_triple = host_target.result.linuxTriple(b.allocator) catch @panic("OOM");
+    const host_cpu = host_target.query.serializeCpuAlloc(b.allocator) catch @panic("OOM");
+    const host_exe_file_ext = host_target.result.exeFileExt();
+    const build_type = b.option(enum { None, Debug, Release, RelWithDebInfo, MinSizeRel }, "build-type", "CMake build type") orelse .Debug;
+    const tool_optimize = b.option(
+        std.builtin.OptimizeMode,
+        "tool-optimize",
+        "Prioritize performance, safety, or binary size for build tools",
+    ) orelse .ReleaseSafe;
+
+    const binaryen_lazy_dep = if (host_target.result.cpu.arch != .aarch64 or host_target.result.os.tag != .windows)
+        b.lazyDependency(b.fmt("binaryen-{s}", .{host_triple}), .{})
+    else
+        null;
+    const cmake_lazy_dep = b.lazyDependency(b.fmt("cmake-{s}", .{host_triple}), .{});
+    const ninja_lazy_dep = b.lazyDependency(b.fmt("ninja-{s}", .{host_triple}), .{});
+    const qemu_lazy_dep = if (host_target.result.cpu.arch == .x86_64 and host_target.result.os.tag == .linux)
+        b.lazyDependency(b.fmt("qemu-{s}", .{host_triple}), .{})
+    else
+        null;
+    const tidy_lazy_dep = b.lazyDependency(b.fmt("tidy-{s}", .{host_triple}), .{});
+    const wasmtime_lazy_dep = if (host_target.result.cpu.arch != .aarch64 or host_target.result.os.tag != .windows)
+        b.lazyDependency(b.fmt("wasmtime-{s}", .{host_triple}), .{})
+    else
+        null;
+    const zig_llvm_lld_clang_lazy_dep =
+        b.lazyDependency(b.fmt("zig+llvm+lld+clang-{s}", .{host_triple}), .{});
+
+    const cmake_dep = cmake_lazy_dep orelse return;
+    const ninja_dep = ninja_lazy_dep orelse return;
+    const tidy_dep = tidy_lazy_dep orelse return;
+    const zig_llvm_lld_clang_dep = zig_llvm_lld_clang_lazy_dep orelse return;
+
+    const cmake_exe = cmake_dep.path(b.fmt("{s}bin/cmake{s}", .{
+        if (host_target.result.isDarwin()) "CMake.app/Contents/" else "",
+        host_exe_file_ext,
+    }));
+    const ninja_exe = ninja_dep.path(b.fmt("ninja{s}", .{host_exe_file_ext}));
+    const tidy_exe = tidy_dep.path(b.fmt("bin/tidy{s}", .{host_exe_file_ext}));
+
+    const build_file = b.path("../build.zig");
+    const local_cache_dir = b.path("zig-local-cache");
+    const global_cache_dir = b.path("zig-global-cache");
+
+    const clean_step = b.step("clean", "Cleanup previous CI runs");
+    clean_step.dependOn(&b.addRemoveDirTree(b.cache_root.path orelse ".").step);
+    clean_step.dependOn(&b.addRemoveDirTree(b.pathFromRoot("../zig-cache")).step);
+    clean_step.dependOn(&b.addRemoveDirTree(local_cache_dir.getPath(b)).step);
+    clean_step.dependOn(&b.addRemoveDirTree(global_cache_dir.getPath(b)).step);
+
+    const run_exe = b.addExecutable(.{
+        .name = "run",
+        .root_source_file = b.path("run.zig"),
+        .target = host_target,
+        .optimize = tool_optimize,
+        .strip = false,
+    });
+    run_exe.step.max_rss = 276_529_152;
+
+    const run_chmod_step = if (host_target.result.isDarwin()) steps: {
+        const chmod_exe = b.addExecutable(.{
+            .name = "chmod",
+            .root_source_file = b.path("chmod.zig"),
+            .target = host_target,
+            .optimize = tool_optimize,
+            .strip = false,
+        });
+        chmod_exe.step.max_rss = 254_050_304;
+
+        const run_chmod = b.addRunArtifact(chmod_exe);
+        run_chmod.step.max_rss = 1_212_416;
+        if (binaryen_lazy_dep) |binaryen_dep| for ([_][]const u8{
+            "binaryen-unittests",
+            "wasm2js",
+            "wasm-as",
+            "wasm-ctor-eval",
+            "wasm-dis",
+            "wasm-emscripten-finalize",
+            "wasm-fuzz-lattices",
+            "wasm-fuzz-types",
+            "wasm-merge",
+            "wasm-metadce",
+            "wasm-opt",
+            "wasm-reduce",
+            "wasm-shell",
+            "wasm-split",
+        }) |exe| run_chmod.addFileArg(binaryen_dep.path(b.fmt("bin/{s}{s}", .{ exe, host_exe_file_ext })));
+        run_chmod.addFileArg(cmake_exe);
+        run_chmod.addFileArg(ninja_exe);
+        if (qemu_lazy_dep) |qemu_dep| for ([_][]const u8{
+            "cris",
+            "mips64el",
+            "ppc64",
+            "loongarch64",
+            "sparc",
+            "aarch64",
+            "sparc64",
+            "alpha",
+            "sparc32plus",
+            "sh4",
+            "hexagon",
+            "xtensaeb",
+            "riscv64",
+            "aarch64_be",
+            "i386",
+            "armeb",
+            "mips",
+            "s390x",
+            "mips64",
+            "ppc64le",
+            "mipsel",
+            "x86_64",
+            "arm",
+            "hppa",
+            "ppc",
+            "or1k",
+            "xtensa",
+            "microblaze",
+            "riscv32",
+            "m68k",
+            "sh4eb",
+            "mipsn32el",
+            "nios2",
+            "microblazeel",
+            "mipsn32",
+        }) |qemu_target| run_chmod.addFileArg(qemu_dep.path(b.fmt("bin/qemu-{s}{s}", .{ qemu_target, host_exe_file_ext })));
+        run_chmod.addFileArg(tidy_exe);
+        if (wasmtime_lazy_dep) |wasmtime_dep| run_chmod.addFileArg(wasmtime_dep.path(b.fmt("wasmtime{s}", .{host_exe_file_ext})));
+        run_chmod.addFileArg(zig_llvm_lld_clang_dep.path(b.fmt("bin/zig{s}", .{host_exe_file_ext})));
+
+        break :steps &run_chmod.step;
+    } else null;
+
+    const build_cc_stage2_step = if (b.option(
+        []const u8,
+        "cc",
+        "System C compiler to use for cc bootstrap",
+    )) |cc| steps: {
+        const cc_bootstrap_step = b.step("cc-bootstrap", "Test cc bootstrap");
+
+        const build_bootstrap = b.addSystemCommand(&.{ cc, "-o" });
+        build_bootstrap.step.max_rss = 93_835_264;
+        const bootstrap_exe = build_bootstrap.addOutputFileArg("bootstrap");
+        build_bootstrap.addArgs(&.{ "-MD", "-MF" });
+        _ = build_bootstrap.addDepFileOutputArg("bootstrap.d");
+        build_bootstrap.addFileArg(b.path("../bootstrap.c"));
+        build_bootstrap.setCwd(b.path(".."));
+
+        const build_stage2 = std.Build.Step.Run.create(b, "build cc bootstrap");
+        build_stage2.step.max_rss = 5_953_224_704;
+        build_stage2.addArtifactArg(run_exe);
+        build_stage2.addArgs(&.{
+            "$0",
+            "--delete",
+            "zig-wasm2c",
+            "zig1.c",
+            "zig1",
+            "config.zig",
+            "zig2.c",
+            "compiler_rt.c",
+            "--rename",
+            "zig2",
+            "$1",
+            "--",
+        });
+        build_stage2.addFileArg(bootstrap_exe);
+        const stage2_exe = build_stage2.addOutputFileArg("zig2");
+        build_stage2.setEnvironmentVariable("CC", cc);
+        build_stage2.setCwd(b.path(".."));
+
+        const build_stage3 = std.Build.Step.Run.create(b, "build cc bootstrap");
+        build_stage3.step.max_rss = 539_484_160;
+        build_stage3.addFileArg(stage2_exe);
+        build_stage3.addArgs(&.{
+            "build",
+            "--maxrss",
+            b.fmt("{}", .{@max(build_stage3.step.max_rss, 7_000_000_000)}),
+            "--build-file",
+        });
+        build_stage3.addFileArg(build_file);
+        build_stage3.addArg("--prefix");
+        const stage3_out = build_stage3.addOutputDirectoryArg("stage3");
+        build_stage3.addArg("--cache-dir");
+        build_stage3.addDirectoryArg(local_cache_dir);
+        build_stage3.addArg("--global-cache-dir");
+        build_stage3.addDirectoryArg(global_cache_dir);
+        build_stage3.addArg("-Dno-lib");
+
+        const run_tests = std.Build.Step.Run.create(b, "test cc bootstrap (stage3)");
+        run_tests.step.max_rss = 451_231_744;
+        run_tests.addFileArg(stage3_out.path(b, b.fmt("bin/zig{s}", .{host_exe_file_ext})));
+        run_tests.addArg("test");
+        run_tests.addFileArg(b.path("../test/behavior.zig"));
+        cc_bootstrap_step.dependOn(&run_tests.step);
+
+        break :steps &build_stage2.step;
+    } else null;
+
+    {
+        const cmake_bootstrap_step = b.step("cmake-bootstrap", "test cmake bootstrap");
+
+        const build_stage3 = std.Build.Step.Run.create(b, "build cmake bootstrap");
+        build_stage3.step.max_rss = 10_620_571_648;
+        build_stage3.addArtifactArg(run_exe);
+        build_stage3.addArgs(&.{
+            "$4",
+            "-GNinja",
+            "-S..",
+            "-B$6",
+            "-DCMAKE_MAKE_PROGRAM=$5",
+            "-DCMAKE_BUILD_TYPE=$2",
+            "-DCMAKE_PREFIX_PATH=$7",
+            "-DCMAKE_C_COMPILER=$7/bin/zig$3;cc;-target;$0;-mcpu=$1",
+            "-DCMAKE_CXX_COMPILER=$7/bin/zig$3;c++;-target;$0;-mcpu=$1",
+            "-DCMAKE_AR=$7/bin/zig$3",
+            "-DZIG_AR_WORKAROUND=ON",
+            "-DZIG_TARGET_TRIPLE=$0",
+            "-DZIG_TARGET_MCPU=$1",
+            "-DZIG_STATIC=ON",
+            "-DZIG_STATIC_CURSES=OFF",
+            "-DZIG_NO_LIB=ON",
+            "--then",
+            "$5",
+            "-C",
+            "$6",
+            "install",
+            "--",
+            host_triple,
+            host_cpu,
+            @tagName(build_type),
+            host_exe_file_ext,
+        });
+        build_stage3.addFileArg(cmake_exe);
+        build_stage3.addFileArg(ninja_exe);
+        const stage3_exe = build_stage3.addOutputDirectoryArg("build")
+            .path(b, b.fmt("stage3/bin/zig{s}", .{host_exe_file_ext}));
+        build_stage3.addDirectoryArg(zig_llvm_lld_clang_dep.path(""));
+        build_stage3.addFileInput(b.path("../stage1/zig1.wasm"));
+        build_stage3.addFileInput(b.path("../stage1/zig.h"));
+        if (run_chmod_step) |step| build_stage3.step.dependOn(step);
+
+        const run_tests = std.Build.Step.Run.create(b, "test cmake bootstrap (stage3)");
+        run_tests.step.max_rss = 12_676_628_480;
+        run_tests.addArtifactArg(run_exe);
+        run_tests.addArgs(&.{
+            "$0",
+            "build",
+            "$--maxrss",
+            b.fmt("{}", .{run_tests.step.max_rss}),
+            "$--build-file",
+            "$1",
+            "$--prefix",
+            "$2",
+            "$--cache-dir",
+            "$3",
+            "$--global-cache-dir",
+            "$4",
+            "test-fmt",
+            "test",
+            "docs",
+            "-Dstatic-llvm",
+            "$--search-prefix",
+            "$5",
+        });
+        if (host_target.result.isDarwin()) run_tests.addArg("-Denable-macos-sdk");
+        if (host_target.result.os.tag == .windows) run_tests.addArgs(&.{"-Denable-symlinks-windows"});
+        if (b.option(bool, "skip-non-native", "Skip non-native tests") orelse false)
+            run_tests.addArg("-Dskip-non-native");
+        if (qemu_lazy_dep) |_| run_tests.addArg("-fqemu");
+        if (wasmtime_lazy_dep) |_| run_tests.addArg("-fwasmtime");
+        run_tests.addArg("--path");
+        {
+            var index: usize = 6;
+            for ([_]?*std.Build.Dependency{
+                qemu_lazy_dep,
+                wasmtime_lazy_dep,
+            }) |mabye_dep| if (mabye_dep) |_| {
+                run_tests.addArg(b.fmt("${}", .{index}));
+                index += 1;
+            };
+        }
+        run_tests.addArg("--");
+        run_tests.addFileArg(stage3_exe);
+        run_tests.addFileArg(build_file);
+        const tests_install = run_tests.addOutputDirectoryArg("tests");
+        run_tests.addDirectoryArg(local_cache_dir);
+        run_tests.addDirectoryArg(global_cache_dir);
+        run_tests.addDirectoryArg(zig_llvm_lld_clang_dep.path(""));
+        if (qemu_lazy_dep) |qemu_dep| run_tests.addDirectoryArg(qemu_dep.path("bin"));
+        if (wasmtime_lazy_dep) |wasmtime_dep| run_tests.addDirectoryArg(wasmtime_dep.path(""));
+        if (run_chmod_step) |step| run_tests.step.dependOn(step);
+        cmake_bootstrap_step.dependOn(&run_tests.step);
+
+        for (b.option([]const []const u8, "extra-target", "Extra targets to build") orelse &.{}) |build_target| {
+            const build_stage4 = std.Build.Step.Run.create(b, "build");
+            build_stage4.step.max_rss = 4_369_842_176;
+            build_stage4.addFileArg(stage3_exe);
+            build_stage4.addArgs(&.{
+                "build",
+                "--maxrss",
+                b.fmt("{}", .{@max(build_stage4.step.max_rss, 7_000_000_000)}),
+                "--build-file",
+            });
+            build_stage4.addFileArg(build_file);
+            build_stage4.addArg("--prefix");
+            _ = build_stage4.addOutputDirectoryArg(b.fmt("stage4-{s}", .{build_target}));
+            build_stage4.addArg("--cache-dir");
+            build_stage4.addDirectoryArg(local_cache_dir);
+            build_stage4.addArg("--global-cache-dir");
+            build_stage4.addDirectoryArg(global_cache_dir);
+            build_stage4.addArgs(&.{ b.fmt("-Dtarget={s}", .{build_target}), "-Dno-lib" });
+            cmake_bootstrap_step.dependOn(&build_stage4.step);
+        }
+
+        {
+            const tidy_step = b.step("tidy", "Look for HTML errors");
+
+            const run_tidy = std.Build.Step.Run.create(b, "run tidy");
+            run_tidy.step.max_rss = 11_943_936;
+            run_tidy.addFileArg(tidy_exe);
+            run_tidy.addArgs(&.{ "--drop-empty-elements", "no", "-quiet", "-errors" });
+            run_tidy.addFileArg(tests_install.path(b, "doc/langref.html"));
+            if (run_chmod_step) |step| run_tidy.step.dependOn(step);
+            tidy_step.dependOn(&run_tidy.step);
+        }
+
+        switch (build_type) {
+            .None, .Debug => {},
+            .Release, .RelWithDebInfo, .MinSizeRel => {
+                const reproducible_step = b.step("reproducible", "Ensure that stage3 and stage4 are byte-for-byte identical");
+
+                const run_stage3_version = std.Build.Step.Run.create(b, "get stage3 version");
+                run_stage3_version.step.max_rss = 40_452_096;
+                run_stage3_version.addFileArg(stage3_exe);
+                run_stage3_version.addArg("version");
+                const stage3_version = run_stage3_version.captureStdOut();
+
+                const build_stage4 = b.addRunArtifact(run_exe);
+                build_stage4.step.max_rss = 4_267_229_184;
+                build_stage4.addArgs(&.{
+                    "$2",
+                    "build",
+                    "$--maxrss",
+                    b.fmt("{}", .{@max(build_stage4.step.max_rss, 7_000_000_000)}),
+                    "$--build-file",
+                    "$3",
+                    "$--prefix",
+                    "$4",
+                    "$--cache-dir",
+                    "$5",
+                    "$--global-cache-dir",
+                    "$6",
+                    "-Denable-llvm",
+                    "-Dno-lib",
+                    "-Doptimize=ReleaseFast",
+                    "-Dstrip",
+                    "-Dtarget=$0",
+                    "-Dcpu=$1",
+                    "-Duse-zig-libcxx",
+                    "-Dversion-string=@7",
+                    "--",
+                    host_triple,
+                    host_cpu,
+                });
+                build_stage4.addFileArg(stage3_exe);
+                build_stage4.addFileArg(build_file);
+                const stage4_prefix = build_stage4.addOutputDirectoryArg("stage4");
+                build_stage4.addDirectoryArg(local_cache_dir);
+                build_stage4.addDirectoryArg(global_cache_dir);
+                build_stage4.addFileArg(stage3_version);
+
+                const cmp_exe = b.addExecutable(.{
+                    .name = "cmp",
+                    .root_source_file = b.path("cmp.zig"),
+                    .target = host_target,
+                    .optimize = tool_optimize,
+                    .strip = false,
+                });
+                cmp_exe.step.max_rss = 267_403_264;
+
+                const run_cmp = std.Build.Step.Run.create(b, "Check stage3 and stage4 are byte-for-byte identical");
+                run_cmp.step.max_rss = 4_698_112;
+                run_cmp.addArtifactArg(cmp_exe);
+                run_cmp.addFileArg(stage3_exe);
+                run_cmp.addFileArg(stage4_prefix.path(b, b.fmt("bin/zig{s}", .{host_exe_file_ext})));
+                reproducible_step.dependOn(&run_cmp.step);
+            },
+        }
+
+        if (binaryen_lazy_dep) |binaryen_dep| {
+            const update_stage1_step = b.step("update-stage1", "Test bootstrap after updating the stage1 wasm binary");
+
+            const update_zig1 = std.Build.Step.Run.create(b, "update zig1");
+            update_zig1.step.max_rss = 1_672_757_248;
+            update_zig1.addArtifactArg(run_exe);
+            update_zig1.addArgs(&.{
+                "$0",
+                "build",
+                "$--maxrss",
+                b.fmt("{}", .{@max(update_zig1.step.max_rss, 7_000_000_000)}),
+                "$--build-file",
+                "$1",
+                "$--cache-dir",
+                "$2",
+                "$--global-cache-dir",
+                "$3",
+                "update-zig1",
+                "--path",
+                "$4",
+                "--",
+            });
+            update_zig1.addFileArg(stage3_exe);
+            update_zig1.addFileArg(build_file);
+            update_zig1.addDirectoryArg(local_cache_dir);
+            update_zig1.addDirectoryArg(global_cache_dir);
+            update_zig1.addDirectoryArg(binaryen_dep.path("bin"));
+            if (run_chmod_step) |step| update_zig1.step.dependOn(step);
+            // Clobbering stage1 depends on all steps that use the original stage1
+            if (build_cc_stage2_step) |step| update_zig1.step.dependOn(step);
+            update_zig1.step.dependOn(&build_stage3.step);
+
+            const build_updated_stage3 = std.Build.Step.Run.create(b, "build updated cmake bootstrap");
+            build_updated_stage3.step.max_rss = 10_600_501_248;
+            build_updated_stage3.addArtifactArg(run_exe);
+            build_updated_stage3.addArgs(&.{
+                "$4",
+                "-GNinja",
+                "-S..",
+                "-B$6",
+                "-DCMAKE_MAKE_PROGRAM=$5",
+                "-DCMAKE_BUILD_TYPE=$2",
+                "-DCMAKE_PREFIX_PATH=$7",
+                "-DCMAKE_C_COMPILER=$7/bin/zig$3;cc;-target;$0;-mcpu=$1",
+                "-DCMAKE_CXX_COMPILER=$7/bin/zig$3;c++;-target;$0;-mcpu=$1",
+                "-DCMAKE_AR=$7/bin/zig$3",
+                "-DZIG_AR_WORKAROUND=ON",
+                "-DZIG_TARGET_TRIPLE=$0",
+                "-DZIG_TARGET_MCPU=$1",
+                "-DZIG_STATIC=ON",
+                "-DZIG_STATIC_CURSES=OFF",
+                "-DZIG_NO_LIB=ON",
+                "--then",
+                "$5",
+                "-C",
+                "$6",
+                "install",
+                "--",
+                host_triple,
+                host_cpu,
+                @tagName(build_type),
+                host_exe_file_ext,
+            });
+            build_updated_stage3.addFileArg(cmake_exe);
+            build_updated_stage3.addFileArg(ninja_exe);
+            const updated_stage3_exe = build_updated_stage3.addOutputDirectoryArg("build")
+                .path(b, b.fmt("stage3/bin/zig{s}", .{host_exe_file_ext}));
+            build_updated_stage3.addDirectoryArg(zig_llvm_lld_clang_dep.path(""));
+            build_updated_stage3.addFileInput(b.path("../stage1/zig1.wasm"));
+            build_updated_stage3.addFileInput(b.path("../stage1/zig.h"));
+            if (run_chmod_step) |step| build_updated_stage3.step.dependOn(step);
+            build_updated_stage3.step.dependOn(&update_zig1.step);
+
+            const build_updated_stage4 = b.addRunArtifact(run_exe);
+            build_updated_stage4.step.max_rss = 4_244_979_712;
+            build_updated_stage4.addArgs(&.{
+                "$2",
+                "build",
+                "$--maxrss",
+                b.fmt("{}", .{@max(build_updated_stage4.step.max_rss, 7_000_000_000)}),
+                "$--build-file",
+                "$3",
+                "$--prefix",
+                "$4",
+                "$--cache-dir",
+                "$5",
+                "$--global-cache-dir",
+                "$6",
+                "-Denable-llvm",
+                "-Dno-lib",
+                "-Doptimize=ReleaseFast",
+                "-Dstrip",
+                "-Dtarget=$0",
+                "-Dcpu=$1",
+                "-Duse-zig-libcxx",
+                "--",
+                host_triple,
+                host_cpu,
+            });
+            build_updated_stage4.addFileArg(updated_stage3_exe);
+            build_updated_stage4.addFileArg(build_file);
+            const updated_stage4_prefix = build_updated_stage4.addOutputDirectoryArg("stage4");
+            build_updated_stage4.addDirectoryArg(local_cache_dir);
+            build_updated_stage4.addDirectoryArg(global_cache_dir);
+
+            const run_tests_with_updated_stage4 = std.Build.Step.Run.create(b, "test updated cmake bootstrap (stage3)");
+            run_tests_with_updated_stage4.step.max_rss = 613_875_712;
+            run_tests_with_updated_stage4.addFileArg(updated_stage4_prefix.path(b, b.fmt("bin/zig{s}", .{host_exe_file_ext})));
+            run_tests_with_updated_stage4.addArg("test");
+            run_tests_with_updated_stage4.addFileArg(b.path("../test/behavior.zig"));
+            update_stage1_step.dependOn(&run_tests_with_updated_stage4.step);
+        }
+
+        msvc: {
+            const msvc_target = target: {
+                var target = host_target.result;
+                target.abi = .msvc;
+                break :target target;
+            };
+            const libc = std.zig.LibCDirs.detect(
+                b.allocator,
+                b.pathFromRoot("../lib"),
+                msvc_target,
+                true,
+                true,
+                null,
+            ) catch |err| switch (err) {
+                else => |e| @panic(@errorName(e)),
+            };
+            const msvc_arch = switch (host_target.result.cpu.arch) {
+                .x86 => "x86",
+                .x86_64 => "x64",
+                .arm, .armeb, .thumb, .thumbeb => "arm",
+                .aarch64 => "arm64",
+                else => break :msvc,
+            };
+            const cl_exe = b.pathResolve(&.{
+                (libc.libc_installation orelse break :msvc).msvc_lib_dir orelse break :msvc,
+                "..",
+                "..",
+                "bin",
+                b.fmt("Host{s}", .{msvc_arch}),
+                msvc_arch,
+                b.fmt("cl{s}", .{host_exe_file_ext}),
+            });
+            const msvc_triple = msvc_target.linuxTriple(b.allocator) catch @panic("OOM");
+
+            const msvc_step = b.step("msvc", "Run the behavior tests compiled with MSVC");
+
+            const build_msvc_behavior_tests = std.Build.Step.Run.create(b, "build msvc behavior tests");
+            build_msvc_behavior_tests.step.max_rss = 213_237_760;
+            build_msvc_behavior_tests.addFileArg(stage3_exe);
+            build_msvc_behavior_tests.addArgs(&.{
+                "test",
+                "-ofmt=c",
+                "--test-no-exec",
+                "-target",
+                msvc_triple,
+                "-lc",
+            });
+            build_msvc_behavior_tests.addFileArg(b.path("../test/behavior.zig"));
+            const behavior_msvc_source =
+                build_msvc_behavior_tests.addPrefixedOutputFileArg("-femit-bin=", "behavior-msvc.c");
+
+            const build_msvc_compiler_rt = std.Build.Step.Run.create(b, "build msvc compiler-rt");
+            build_msvc_compiler_rt.step.max_rss = 173_846_528;
+            build_msvc_compiler_rt.addFileArg(stage3_exe);
+            build_msvc_compiler_rt.addArgs(&.{
+                "build-obj",
+                "-ofmt=c",
+                "-OReleaseSmall",
+                "--name",
+                "compiler_rt",
+                "-target",
+                msvc_triple,
+                "-lc",
+            });
+            build_msvc_compiler_rt.addFileArg(b.path("../lib/compiler_rt.zig"));
+            const compiler_rt_msvc_source =
+                build_msvc_compiler_rt.addPrefixedOutputFileArg("-femit-bin=", "compiler_rt-msvc.c");
+
+            const build_msvc_tests = std.Build.Step.Run.create(b, "build msvc tests");
+            build_msvc_tests.step.max_rss = 556_036_096;
+            build_msvc_tests.addArgs(&.{ cl_exe, "/W3", "/Z7" });
+            build_msvc_tests.addPrefixedDirectoryArg("/I", b.path("../lib"));
+            build_msvc_tests.addFileArg(behavior_msvc_source);
+            build_msvc_tests.addFileArg(compiler_rt_msvc_source);
+            const msvc_tests_exe = build_msvc_tests.addPrefixedOutputFileArg(
+                "/Fe:",
+                b.fmt("behavior-msvc{s}", .{host_exe_file_ext}),
+            );
+            // Link args must appear after all other args.
+            build_msvc_tests.addArgs(&.{
+                "/link",
+                "/nologo",
+                "/debug",
+                "/subsystem:console",
+                "kernel32.lib",
+                "ntdll.lib",
+                "libcmt.lib",
+            });
+            build_msvc_tests.setEnvironmentVariable("INCLUDE", std.mem.join(
+                b.allocator,
+                &.{std.fs.path.delimiter},
+                libc.libc_include_dir_list,
+            ) catch @panic("OOM"));
+            build_msvc_tests.setEnvironmentVariable("LIB", std.mem.join(
+                b.allocator,
+                &.{std.fs.path.delimiter},
+                &.{
+                    libc.libc_installation.?.msvc_lib_dir.?,
+                    libc.libc_installation.?.crt_dir.?,
+                    libc.libc_installation.?.kernel32_lib_dir.?,
+                },
+            ) catch @panic("OOM"));
+
+            const run_msvc_tests = std.Build.Step.Run.create(b, "run msvc tests");
+            run_msvc_tests.step.max_rss = 6_459_392;
+            run_msvc_tests.addFileArg(msvc_tests_exe);
+            msvc_step.dependOn(&run_msvc_tests.step);
+        }
+    }
+}
diff --git a/ci/build.zig.zon b/ci/build.zig.zon
new file mode 100644
index 000000000000..4d8f5cf39609
--- /dev/null
+++ b/ci/build.zig.zon
@@ -0,0 +1,188 @@
+.{
+    .name = "zig/ci",
+    .version = "0.0.0",
+    .paths = .{""},
+    .dependencies = .{
+        .@"binaryen-x86_64-linux-musl" = .{
+            .hash = "12207d5dd577b7cc822cc007bdc06411fac7f536243afff77f6a181df1987f99b610",
+            .url = "https://github.com/WebAssembly/binaryen/releases/download/version_117/binaryen-version_117-x86_64-linux.tar.gz",
+            .lazy = true,
+        },
+        .@"binaryen-aarch64-linux-musl" = .{
+            .hash = "12207fa9d8edc6d3cb3e56ad5df7ed6205bea4a0712946d1115689ec4e8b6c6013c7",
+            .url = "https://github.com/WebAssembly/binaryen/releases/download/version_117/binaryen-version_117-aarch64-linux.tar.gz",
+            .lazy = true,
+        },
+        .@"binaryen-x86_64-macos-none" = .{
+            .hash = "12207e36613e24971953f70ee13654f5b91a279f95f71c930702ba913878b19a91d3",
+            .url = "https://github.com/WebAssembly/binaryen/releases/download/version_117/binaryen-version_117-x86_64-macos.tar.gz",
+            .lazy = true,
+        },
+        .@"binaryen-aarch64-macos-none" = .{
+            .hash = "122042c3690f6a477febcb4c68568c03bd3409c517e0d9037e06010fff003a4efcc0",
+            .url = "https://github.com/WebAssembly/binaryen/releases/download/version_117/binaryen-version_117-arm64-macos.tar.gz",
+            .lazy = true,
+        },
+        .@"binaryen-x86_64-windows-gnu" = .{
+            .hash = "122046d1b9b8e32c6198520178862b2079ffd2021a03a1f5f8dd6f5b474672dd0217",
+            .url = "https://github.com/WebAssembly/binaryen/releases/download/version_117/binaryen-version_117-x86_64-windows.tar.gz",
+            .lazy = true,
+        },
+
+        .@"cmake-x86_64-linux-musl" = .{
+            .hash = "1220e08f2db1f68d20caeb41d923d1e468ef53e0973d02c1a00c2d517b011e121c40",
+            .url = "https://github.com/Kitware/CMake/releases/download/v3.29.2/cmake-3.29.2-linux-x86_64.tar.gz",
+            .lazy = true,
+        },
+        .@"cmake-aarch64-linux-musl" = .{
+            .hash = "1220a16a663bb2be43a236cb945bac8957be27c6edac8f630e81123fc99f7b2b2de9",
+            .url = "https://github.com/Kitware/CMake/releases/download/v3.29.2/cmake-3.29.2-linux-aarch64.tar.gz",
+            .lazy = true,
+        },
+        .@"cmake-x86_64-macos-none" = .{
+            .hash = "1220d158a5c05cfa2f20d339ec5503c79e96d61a21fe81fd6710c815f2cdcf6e3da0",
+            .url = "https://github.com/Kitware/CMake/releases/download/v3.29.2/cmake-3.29.2-macos-universal.tar.gz",
+            .lazy = true,
+        },
+        .@"cmake-aarch64-macos-none" = .{
+            .hash = "1220d158a5c05cfa2f20d339ec5503c79e96d61a21fe81fd6710c815f2cdcf6e3da0",
+            .url = "https://github.com/Kitware/CMake/releases/download/v3.29.2/cmake-3.29.2-macos-universal.tar.gz",
+            .lazy = true,
+        },
+        .@"cmake-x86_64-windows-gnu" = .{
+            .hash = "12204ff75c21a274e8d4803b77d4699d37f42974d039e398b28cdea7ea2cc1fa3376",
+            .url = "https://github.com/Kitware/CMake/releases/download/v3.29.2/cmake-3.29.2-windows-x86_64.zip",
+            .lazy = true,
+        },
+        .@"cmake-aarch64-windows-gnu" = .{
+            .hash = "12201d1c55e49eecfcbcf0347af9edc4396c2f3a12ab682f3da61d6f310b617753a2",
+            .url = "https://github.com/Kitware/CMake/releases/download/v3.29.2/cmake-3.29.2-windows-arm64.zip",
+            .lazy = true,
+        },
+
+        .@"ninja-x86_64-linux-musl" = .{
+            .hash = "12206a681b6a380e8b380120f8c4e6688bc67b587b01091b019d722f74dca33ad012",
+            .url = "https://github.com/ninja-build/ninja/releases/download/v1.12.0/ninja-linux.zip",
+            .lazy = true,
+        },
+        .@"ninja-aarch64-linux-musl" = .{
+            .hash = "1220480757926ac5ade22fc2a4b39bde33e03480eb0d5e7087474ca4b81b8426e6b6",
+            .url = "https://github.com/ninja-build/ninja/releases/download/v1.12.0/ninja-linux-aarch64.zip",
+            .lazy = true,
+        },
+        .@"ninja-x86_64-macos-none" = .{
+            .hash = "1220978a9f52d9dff7614814ec52381aa709ea63a333249549c02f0b917c65733f5a",
+            .url = "https://github.com/ninja-build/ninja/releases/download/v1.12.0/ninja-mac.zip",
+            .lazy = true,
+        },
+        .@"ninja-aarch64-macos-none" = .{
+            .hash = "1220978a9f52d9dff7614814ec52381aa709ea63a333249549c02f0b917c65733f5a",
+            .url = "https://github.com/ninja-build/ninja/releases/download/v1.12.0/ninja-mac.zip",
+            .lazy = true,
+        },
+        .@"ninja-x86_64-windows-gnu" = .{
+            .hash = "1220543c9071fd6d5f16d2d5a64473cf252266b2928f9947c3b87a87de6d983724df",
+            .url = "https://github.com/ninja-build/ninja/releases/download/v1.12.0/ninja-win.zip",
+            .lazy = true,
+        },
+        .@"ninja-aarch64-windows-gnu" = .{
+            .hash = "12207d071c13ee8539a3445ea198243c12c917492411c3e7dfd8b54ff1714d759a73",
+            .url = "https://github.com/ninja-build/ninja/releases/download/v1.12.0/ninja-winarm64.zip",
+            .lazy = true,
+        },
+
+        .@"qemu-x86_64-linux-musl" = .{
+            .hash = "122077e46a30ef6fee9b98aedc50bc613a5d37c038d2ac823445951d1cd8bbc0e162",
+            .url = "https://ziglang.org/deps/qemu-linux-x86_64-8.2.1.tar.xz",
+            .lazy = true,
+        },
+
+        .@"tidy-x86_64-linux-musl" = .{
+            .hash = "1220b07c11837da15ae5f44201327cf3a1d554c650b384429f48d8234be8942ddc9d",
+            .url = "https://github.com/jacobly0/zig-tidy/releases/download/5.8.0/tidy-5.8.0-x86_64-linux-musl.tar.xz",
+            .lazy = true,
+        },
+        .@"tidy-aarch64-linux-musl" = .{
+            .hash = "122006a2ede0400f00789abe48e47861e5bbab7f8ca16789db4bd9e351299c4ac590",
+            .url = "https://github.com/jacobly0/zig-tidy/releases/download/5.8.0/tidy-5.8.0-aarch64-linux-musl.tar.xz",
+            .lazy = true,
+        },
+        .@"tidy-x86_64-macos-none" = .{
+            .hash = "1220f18256987f627618a21fde39f3cda13ac7bd6f01f35c9ccbb9e07ea81ca77cfc",
+            .url = "https://github.com/jacobly0/zig-tidy/releases/download/5.8.0/tidy-5.8.0-x86_64-macos-none.tar.xz",
+            .lazy = true,
+        },
+        .@"tidy-aarch64-macos-none" = .{
+            .hash = "1220a8ee39addf48e3be546616fe14853e3db1cb49522bd90a24bade371330176826",
+            .url = "https://github.com/jacobly0/zig-tidy/releases/download/5.8.0/tidy-5.8.0-aarch64-macos-none.tar.xz",
+            .lazy = true,
+        },
+        .@"tidy-x86_64-windows-gnu" = .{
+            .hash = "12205c2cb107a59e552947a51a302296912bd097fcf1414e9a7521ce8ededb915574",
+            .url = "https://github.com/jacobly0/zig-tidy/releases/download/5.8.0/tidy-5.8.0-x86_64-windows-gnu.zip",
+            .lazy = true,
+        },
+        .@"tidy-aarch64-windows-gnu" = .{
+            .hash = "1220dce14dc654e391c06c7e1d5b078355195286350cb8cab8e1f21f3a08df716736",
+            .url = "https://github.com/jacobly0/zig-tidy/releases/download/5.8.0/tidy-5.8.0-aarch64-windows-gnu.zip",
+            .lazy = true,
+        },
+
+        .@"wasmtime-x86_64-linux-musl" = .{
+            .hash = "122062e8c3f052636b68b60f096eab11618a010ee67e5ec772d5c41362e471c30607",
+            .url = "https://github.com/bytecodealliance/wasmtime/releases/download/v13.0.1/wasmtime-v13.0.1-x86_64-linux.tar.xz",
+            .lazy = true,
+        },
+        .@"wasmtime-aarch64-linux-musl" = .{
+            .hash = "122069362558cae6da16d5de27a23b793bcd604bbbeb908ee8af25a1f9e48ce0d87b",
+            .url = "https://github.com/bytecodealliance/wasmtime/releases/download/v13.0.1/wasmtime-v13.0.1-aarch64-linux.tar.xz",
+            .lazy = true,
+        },
+        .@"wasmtime-x86_64-macos-none" = .{
+            .hash = "12205fbb7d93b7e41f74565b1b8df5862834d5b8e1676ad9d5814127f8ea79c6d923",
+            .url = "https://github.com/bytecodealliance/wasmtime/releases/download/v13.0.1/wasmtime-v13.0.1-x86_64-macos.tar.xz",
+            .lazy = true,
+        },
+        .@"wasmtime-aarch64-macos-none" = .{
+            .hash = "122021a51bda85da636583101f1815432b4b421d1506db459640af13fe28795ad5a0",
+            .url = "https://github.com/bytecodealliance/wasmtime/releases/download/v13.0.1/wasmtime-v13.0.1-aarch64-macos.tar.xz",
+            .lazy = true,
+        },
+        .@"wasmtime-x86_64-windows-gnu" = .{
+            .hash = "12206dd597841bb2e048996c650ae66b621c25c0e59d2555b4abf242d4b6deb16151",
+            .url = "https://github.com/bytecodealliance/wasmtime/releases/download/v13.0.1/wasmtime-v13.0.1-x86_64-windows.zip",
+            .lazy = true,
+        },
+
+        .@"zig+llvm+lld+clang-x86_64-linux-musl" = .{
+            .hash = "122038e9a69ea4c220fcb5fb1959f203d37cc38b0f741b31baa04c7fb91cdc2a2c5f",
+            .url = "https://ziglang.org/deps/zig+llvm+lld+clang-x86_64-linux-musl-0.12.0-dev.203+d3bc1cfc4.tar.xz",
+            .lazy = true,
+        },
+        .@"zig+llvm+lld+clang-aarch64-linux-musl" = .{
+            .hash = "1220ab0638018efa29874ef3f8af270ccd1d3b789770aacff5f26a8761bf2310c17f",
+            .url = "https://ziglang.org/deps/zig+llvm+lld+clang-aarch64-linux-musl-0.12.0-dev.203+d3bc1cfc4.tar.xz",
+            .lazy = true,
+        },
+        .@"zig+llvm+lld+clang-x86_64-macos-none" = .{
+            .hash = "12200a696f4021689c7a36a10f5751a01e1cc3b1a8b22ca6f3dc3bc9641b6aed18a2",
+            .url = "https://ziglang.org/deps/zig+llvm+lld+clang-x86_64-macos-none-0.12.0-dev.203+d3bc1cfc4.tar.xz",
+            .lazy = true,
+        },
+        .@"zig+llvm+lld+clang-aarch64-macos-none" = .{
+            .hash = "12208d9d5b5a69efd9f9e5750c51a12a32b3d224365a68e75d93e9c0b77ac9e477dc",
+            .url = "https://ziglang.org/deps/zig+llvm+lld+clang-aarch64-macos-none-0.12.0-dev.203+d3bc1cfc4.tar.xz",
+            .lazy = true,
+        },
+        .@"zig+llvm+lld+clang-x86_64-windows-gnu" = .{
+            .hash = "122014a0dcbb2f485fd0984627f65b0ad03a9ab93c1ce3153d50377ef1757bbf4c44",
+            .url = "https://ziglang.org/deps/zig+llvm+lld+clang-x86_64-windows-gnu-0.12.0-dev.2073+402fe565a.zip",
+            .lazy = true,
+        },
+        .@"zig+llvm+lld+clang-aarch64-windows-gnu" = .{
+            .hash = "1220a8122f2dd5df9e383e9c0bdc2ebbf97e16f595ff5e50be003401c16c14182515",
+            .url = "https://jacobly.com/deps/zig+llvm+lld+clang-aarch64-windows-gnu-0.12.0-dev.72+5bbb2f966.zip",
+            .lazy = true,
+        },
+    },
+}
diff --git a/ci/chmod.zig b/ci/chmod.zig
new file mode 100644
index 000000000000..c0c1e5c8ce80
--- /dev/null
+++ b/ci/chmod.zig
@@ -0,0 +1,32 @@
+const std = @import("std");
+
+pub fn main() !void {
+    var args_it = try std.process.argsWithAllocator(std.heap.page_allocator);
+    defer args_it.deinit();
+    _ = args_it.skip();
+    while (args_it.next()) |path| {
+        const file = std.fs.cwd().openFile(path, .{}) catch |err| switch (err) {
+            error.FileNotFound, error.NotDir => continue,
+            else => |e| return e,
+        };
+        defer file.close();
+        var got_access_denied = false;
+        while (true) {
+            const old_mode = try file.mode();
+            const new_mode = old_mode | (std.posix.S.IXUSR | std.posix.S.IXGRP | std.posix.S.IXOTH);
+            if (new_mode != old_mode) file.chmod(new_mode) catch |err| switch (err) {
+                // This can happen on macOS during a race condition where another process adds the
+                // executable bits and executes the file between this process reading the old mode
+                // and setting the new mode.  In the case, getting the mode again will return the
+                // newly set executable bits and so this code will not be reached the second time.
+                error.AccessDenied => |e| {
+                    if (got_access_denied) return e;
+                    got_access_denied = true;
+                    continue;
+                },
+                else => |e| return e,
+            };
+            break;
+        }
+    }
+}
diff --git a/ci/cmp.zig b/ci/cmp.zig
new file mode 100644
index 000000000000..705bc3bc1137
--- /dev/null
+++ b/ci/cmp.zig
@@ -0,0 +1,28 @@
+const std = @import("std");
+
+pub fn main() !void {
+    var args = try std.process.argsWithAllocator(std.heap.page_allocator);
+    _ = args.skip();
+    const first_path = args.next().?;
+    const first_file = try std.fs.cwd().openFile(first_path, .{});
+    const second_path = args.next().?;
+    const second_file = try std.fs.cwd().openFile(second_path, .{});
+
+    var first_buffer: [1 << 18]u8 = undefined;
+    var second_buffer: [1 << 18]u8 = undefined;
+    var offset: u64 = 0;
+    while (true) {
+        const first_data = first_buffer[0..try first_file.reader().readAll(&first_buffer)];
+        const second_data = second_buffer[0..try second_file.reader().readAll(&second_buffer)];
+        if (std.mem.indexOfDiff(u8, first_data, second_data)) |diff_index| {
+            try std.io.getStdErr().writer().print("{s} {s} differ: byte {d}\n", .{
+                first_path,
+                second_path,
+                offset + diff_index + 1,
+            });
+            std.process.exit(1);
+        }
+        offset += first_data.len;
+        if (first_data.len < first_buffer.len) break;
+    }
+}
diff --git a/ci/run.zig b/ci/run.zig
new file mode 100644
index 000000000000..d1b8b1a95abd
--- /dev/null
+++ b/ci/run.zig
@@ -0,0 +1,126 @@
+//! ./runner command0 [arg0 arg1 ...] [--then command1 arg0 arg1 ...] [--path path0 path1 ...] [--cwd cwd] [--delete file0 file1 ...] [--rename old0 new0 [old1 new1 ...]] -- [replacement0 replacement1 ... replacement9]
+//! Replaces $0 through $9 in all non-option arguments with replacement0 through replacement9,
+//! which have native path separators replaced with posix path separators.
+//! Replaces @0 through @9 in all non-option arguments with the contents of the file
+//! replacement0 through replacement9.
+//! Then, executes the command before any option arguments with extra paths after --path and at optional cwd after --cwd.
+//! Then, executes the command after --then with extra paths after --path and at optional cwd after --cwd.
+//! Then, optionally deletes files after --delete.
+//! Then, optionally renomes pairs of files after --rename.
+
+const std = @import("std");
+
+pub fn main() !void {
+    var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
+    const allocator = arena.allocator();
+
+    const args = try std.process.argsAlloc(allocator);
+    var first: [][]u8 = &.{};
+    var then: [][]u8 = &.{};
+    var cwd: [][]u8 = &.{};
+    var path: [][]u8 = &.{};
+    var delete: [][]u8 = &.{};
+    var rename: [][]u8 = &.{};
+    var replacements: [][]u8 = &.{};
+
+    var prev_separator_index: usize = 0;
+    var separator_index: usize = 1;
+    while (separator_index < args.len) : (separator_index += 1) {
+        if (!std.mem.startsWith(u8, args[separator_index], "--")) continue;
+        const separated_args = args[prev_separator_index + 1 .. separator_index];
+        if (prev_separator_index == 0)
+            first = separated_args
+        else if (std.mem.eql(u8, args[prev_separator_index], "--then"))
+            then = separated_args
+        else if (std.mem.eql(u8, args[prev_separator_index], "--cwd"))
+            cwd = separated_args
+        else if (std.mem.eql(u8, args[prev_separator_index], "--path"))
+            path = separated_args
+        else if (std.mem.eql(u8, args[prev_separator_index], "--delete"))
+            delete = separated_args
+        else if (std.mem.eql(u8, args[prev_separator_index], "--rename"))
+            rename = separated_args
+        else
+            std.debug.panic("unexpected '{s}'", .{args[prev_separator_index]});
+        if (args[separator_index].len == 2) {
+            replacements = args[separator_index + 1 ..];
+            break;
+        }
+        prev_separator_index = separator_index;
+    } else std.debug.panic("expected '--'", .{});
+
+    if (first.len == 0) std.debug.panic("expected arguments", .{});
+    if (cwd.len > 1) std.debug.panic("expected at most 1 cwd argument", .{});
+    if (rename.len % 2 != 0) std.debug.panic("expected even rename arguments", .{});
+
+    for (replacements) |replacement| std.mem.replaceScalar(
+        u8,
+        replacement,
+        std.fs.path.sep,
+        std.fs.path.sep_posix,
+    );
+    for ([_][][]u8{ first, then, cwd, path, delete, rename }) |patterns| for (patterns) |*pattern| {
+        var replaced = std.ArrayList(u8).init(allocator);
+        var pos: usize = 0;
+        while (std.mem.indexOfAnyPos(u8, pattern.*, pos, "$@")) |special_pos| {
+            try replaced.appendSlice(pattern.*[pos..special_pos]);
+            const special = pattern.*[special_pos..][0..2];
+            if (std.fmt.charToDigit(special[1], 10)) |special_index| switch (special[0]) {
+                '$' => try replaced.appendSlice(replacements[special_index]),
+                '@' => {
+                    const special_file = try std.fs.cwd().openFile(replacements[special_index], .{});
+                    defer special_file.close();
+                    try special_file.reader().readAllArrayList(&replaced, 1 << 12);
+                    replaced.shrinkRetainingCapacity(std.mem.trimRight(u8, replaced.items, &std.ascii.whitespace).len);
+                },
+                else => unreachable,
+            } else |_| switch (special[0]) {
+                '$' => try replaced.append(special[1]),
+                else => unreachable,
+            }
+            pos = special_pos + 2;
+        }
+        try replaced.appendSlice(pattern.*[pos..]);
+        pattern.* = replaced.items;
+    };
+
+    var path_buffer = std.ArrayList(u8).init(allocator);
+    for (path) |path_path| {
+        try path_buffer.appendSlice(path_path);
+        try path_buffer.append(std.fs.path.delimiter);
+    }
+    var env = try std.process.getEnvMap(allocator);
+    if (env.getPtr("PATH")) |env_path| {
+        try path_buffer.appendSlice(env_path.*);
+        env_path.* = try path_buffer.toOwnedSlice();
+    } else if (path_buffer.items.len > 0) try env.putMove(
+        try allocator.dupe(u8, "PATH"),
+        path_buffer.items[0 .. path_buffer.items.len - 1],
+    );
+
+    var first_child = std.process.Child.init(first, allocator);
+    first_child.env_map = &env;
+    if (cwd.len == 1) first_child.cwd = cwd[0];
+    switch (try first_child.spawnAndWait()) {
+        .Exited => |status| if (status != 0) std.process.exit(status),
+        else => |term| std.debug.panic("{}", .{term}),
+    }
+
+    if (then.len > 0) {
+        var then_child = std.process.Child.init(then, allocator);
+        then_child.env_map = &env;
+        if (cwd.len == 1) then_child.cwd = cwd[0];
+        switch (try then_child.spawnAndWait()) {
+            .Exited => |status| if (status != 0) std.process.exit(status),
+            else => |term| std.debug.panic("{}", .{term}),
+        }
+    }
+
+    for (delete) |delete_path| try std.fs.cwd().deleteFile(delete_path);
+
+    var rename_index: usize = 0;
+    while (rename_index < rename.len) : (rename_index += 2) try std.fs.cwd().rename(
+        rename[rename_index + 0],
+        rename[rename_index + 1],
+    );
+}
diff --git a/ci/x86_64-linux-debug.sh b/ci/x86_64-linux-debug.sh
deleted file mode 100755
index 38b98cc4a9fa..000000000000
--- a/ci/x86_64-linux-debug.sh
+++ /dev/null
@@ -1,118 +0,0 @@
-#!/bin/sh
-
-# Requires cmake ninja-build
-
-set -x
-set -e
-
-ARCH="$(uname -m)"
-TARGET="$ARCH-linux-musl"
-MCPU="baseline"
-CACHE_BASENAME="zig+llvm+lld+clang-$TARGET-0.12.0-dev.203+d3bc1cfc4"
-PREFIX="$HOME/deps/$CACHE_BASENAME"
-ZIG="$PREFIX/bin/zig"
-
-export PATH="$HOME/deps/wasmtime-v10.0.2-$ARCH-linux:$HOME/deps/qemu-linux-x86_64-8.2.1/bin:$PATH"
-
-# Make the `zig version` number consistent.
-# This will affect the cmake command below.
-git fetch --unshallow || true
-git fetch --tags
-
-# Test building from source without LLVM.
-git clean -fd
-rm -rf zig-out
-cc -o bootstrap bootstrap.c
-./bootstrap
-./zig2 build -Dno-lib
-./zig-out/bin/zig test test/behavior.zig
-
-export CC="$ZIG cc -target $TARGET -mcpu=$MCPU"
-export CXX="$ZIG c++ -target $TARGET -mcpu=$MCPU"
-
-rm -rf build-debug
-mkdir build-debug
-cd build-debug
-
-# Override the cache directories because they won't actually help other CI runs
-# which will be testing alternate versions of zig, and ultimately would just
-# fill up space on the hard drive for no reason.
-export ZIG_GLOBAL_CACHE_DIR="$PWD/zig-global-cache"
-export ZIG_LOCAL_CACHE_DIR="$PWD/zig-local-cache"
-
-cmake .. \
-  -DCMAKE_INSTALL_PREFIX="stage3-debug" \
-  -DCMAKE_PREFIX_PATH="$PREFIX" \
-  -DCMAKE_BUILD_TYPE=Debug \
-  -DZIG_TARGET_TRIPLE="$TARGET" \
-  -DZIG_TARGET_MCPU="$MCPU" \
-  -DZIG_STATIC=ON \
-  -DZIG_NO_LIB=ON \
-  -GNinja
-
-# Now cmake will use zig as the C/C++ compiler. We reset the environment variables
-# so that installation and testing do not get affected by them.
-unset CC
-unset CXX
-
-ninja install
-
-# TODO: move this to a build.zig step (check-fmt)
-echo "Looking for non-conforming code formatting..."
-stage3-debug/bin/zig fmt --check .. \
-  --exclude ../test/cases/ \
-  --exclude ../doc/ \
-  --exclude ../build-debug
-
-# simultaneously test building self-hosted without LLVM and with 32-bit arm
-stage3-debug/bin/zig build \
-  -Dtarget=arm-linux-musleabihf \
-  -Dno-lib
-
-stage3-debug/bin/zig build test docs \
-  --maxrss 21000000000 \
-  -fqemu \
-  -fwasmtime \
-  -Dstatic-llvm \
-  -Dtarget=native-native-musl \
-  --search-prefix "$PREFIX" \
-  --zig-lib-dir "$PWD/../lib"
-
-# Look for HTML errors.
-# TODO: move this to a build.zig flag (-Denable-tidy)
-tidy --drop-empty-elements no -qe "../zig-out/doc/langref.html"
-
-# Ensure that updating the wasm binary from this commit will result in a viable build.
-stage3-debug/bin/zig build update-zig1
-
-rm -rf ../build-new
-mkdir ../build-new
-cd ../build-new
-
-export ZIG_GLOBAL_CACHE_DIR="$PWD/zig-global-cache"
-export ZIG_LOCAL_CACHE_DIR="$PWD/zig-local-cache"
-export CC="$ZIG cc -target $TARGET -mcpu=$MCPU"
-export CXX="$ZIG c++ -target $TARGET -mcpu=$MCPU"
-
-cmake .. \
-  -DCMAKE_PREFIX_PATH="$PREFIX" \
-  -DCMAKE_BUILD_TYPE=Debug \
-  -DZIG_TARGET_TRIPLE="$TARGET" \
-  -DZIG_TARGET_MCPU="$MCPU" \
-  -DZIG_STATIC=ON \
-  -DZIG_NO_LIB=ON \
-  -GNinja
-
-unset CC
-unset CXX
-
-ninja install
-
-stage3/bin/zig test ../test/behavior.zig
-stage3/bin/zig build -p stage4 \
-  -Dstatic-llvm \
-  -Dtarget=native-native-musl \
-  -Dno-lib \
-  --search-prefix "$PREFIX" \
-  --zig-lib-dir "$PWD/../lib"
-stage4/bin/zig test ../test/behavior.zig
diff --git a/ci/x86_64-linux-release.sh b/ci/x86_64-linux-release.sh
deleted file mode 100755
index 3860cd734fe9..000000000000
--- a/ci/x86_64-linux-release.sh
+++ /dev/null
@@ -1,135 +0,0 @@
-#!/bin/sh
-
-# Requires cmake ninja-build
-
-set -x
-set -e
-
-ARCH="$(uname -m)"
-TARGET="$ARCH-linux-musl"
-MCPU="baseline"
-CACHE_BASENAME="zig+llvm+lld+clang-$TARGET-0.12.0-dev.203+d3bc1cfc4"
-PREFIX="$HOME/deps/$CACHE_BASENAME"
-ZIG="$PREFIX/bin/zig"
-
-export PATH="$HOME/deps/wasmtime-v10.0.2-$ARCH-linux:$HOME/deps/qemu-linux-x86_64-8.2.1/bin:$PATH"
-
-# Make the `zig version` number consistent.
-# This will affect the cmake command below.
-git fetch --unshallow || true
-git fetch --tags
-
-# Test building from source without LLVM.
-git clean -fd
-rm -rf zig-out
-cc -o bootstrap bootstrap.c
-./bootstrap
-./zig2 build -Dno-lib
-./zig-out/bin/zig test test/behavior.zig
-
-export CC="$ZIG cc -target $TARGET -mcpu=$MCPU"
-export CXX="$ZIG c++ -target $TARGET -mcpu=$MCPU"
-
-rm -rf build-release
-mkdir build-release
-cd build-release
-
-# Override the cache directories because they won't actually help other CI runs
-# which will be testing alternate versions of zig, and ultimately would just
-# fill up space on the hard drive for no reason.
-export ZIG_GLOBAL_CACHE_DIR="$PWD/zig-global-cache"
-export ZIG_LOCAL_CACHE_DIR="$PWD/zig-local-cache"
-
-cmake .. \
-  -DCMAKE_INSTALL_PREFIX="stage3-release" \
-  -DCMAKE_PREFIX_PATH="$PREFIX" \
-  -DCMAKE_BUILD_TYPE=Release \
-  -DZIG_TARGET_TRIPLE="$TARGET" \
-  -DZIG_TARGET_MCPU="$MCPU" \
-  -DZIG_STATIC=ON \
-  -DZIG_NO_LIB=ON \
-  -GNinja
-
-# Now cmake will use zig as the C/C++ compiler. We reset the environment variables
-# so that installation and testing do not get affected by them.
-unset CC
-unset CXX
-
-ninja install
-
-# TODO: move this to a build.zig step (check-fmt)
-echo "Looking for non-conforming code formatting..."
-stage3-release/bin/zig fmt --check .. \
-  --exclude ../test/cases/ \
-  --exclude ../doc/ \
-  --exclude ../build-debug \
-  --exclude ../build-release
-
-# simultaneously test building self-hosted without LLVM and with 32-bit arm
-stage3-release/bin/zig build \
-  -Dtarget=arm-linux-musleabihf \
-  -Dno-lib
-
-stage3-release/bin/zig build test docs \
-  --maxrss 21000000000 \
-  -fqemu \
-  -fwasmtime \
-  -Dstatic-llvm \
-  -Dtarget=native-native-musl \
-  --search-prefix "$PREFIX" \
-  --zig-lib-dir "$PWD/../lib"
-
-# Look for HTML errors.
-# TODO: move this to a build.zig flag (-Denable-tidy)
-tidy --drop-empty-elements no -qe "../zig-out/doc/langref.html"
-
-# Ensure that stage3 and stage4 are byte-for-byte identical.
-stage3-release/bin/zig build \
-  --prefix stage4-release \
-  -Denable-llvm \
-  -Dno-lib \
-  -Doptimize=ReleaseFast \
-  -Dstrip \
-  -Dtarget=$TARGET \
-  -Duse-zig-libcxx \
-  -Dversion-string="$(stage3-release/bin/zig version)"
-
-# diff returns an error code if the files differ.
-echo "If the following command fails, it means nondeterminism has been"
-echo "introduced, making stage3 and stage4 no longer byte-for-byte identical."
-diff stage3-release/bin/zig stage4-release/bin/zig
-
-# Ensure that updating the wasm binary from this commit will result in a viable build.
-stage3-release/bin/zig build update-zig1
-
-rm -rf ../build-new
-mkdir ../build-new
-cd ../build-new
-
-export ZIG_GLOBAL_CACHE_DIR="$PWD/zig-global-cache"
-export ZIG_LOCAL_CACHE_DIR="$PWD/zig-local-cache"
-export CC="$ZIG cc -target $TARGET -mcpu=$MCPU"
-export CXX="$ZIG c++ -target $TARGET -mcpu=$MCPU"
-
-cmake .. \
-  -DCMAKE_PREFIX_PATH="$PREFIX" \
-  -DCMAKE_BUILD_TYPE=Release \
-  -DZIG_TARGET_TRIPLE="$TARGET" \
-  -DZIG_TARGET_MCPU="$MCPU" \
-  -DZIG_STATIC=ON \
-  -DZIG_NO_LIB=ON \
-  -GNinja
-
-unset CC
-unset CXX
-
-ninja install
-
-stage3/bin/zig test ../test/behavior.zig
-stage3/bin/zig build -p stage4 \
-  -Dstatic-llvm \
-  -Dtarget=native-native-musl \
-  -Dno-lib \
-  --search-prefix "$PREFIX" \
-  --zig-lib-dir "$PWD/../lib"
-stage4/bin/zig test ../test/behavior.zig
diff --git a/ci/x86_64-macos-release.sh b/ci/x86_64-macos-release.sh
deleted file mode 100755
index c67613d3fcfc..000000000000
--- a/ci/x86_64-macos-release.sh
+++ /dev/null
@@ -1,79 +0,0 @@
-#!/bin/sh
-
-set -x
-set -e
-
-ZIGDIR="$PWD"
-TARGET="$ARCH-macos-none"
-MCPU="baseline"
-CACHE_BASENAME="zig+llvm+lld+clang-$TARGET-0.12.0-dev.467+0345d7866"
-PREFIX="$HOME/$CACHE_BASENAME"
-JOBS="-j3"
-
-rm -rf $PREFIX
-cd $HOME
-
-curl -L -O "https://ziglang.org/deps/$CACHE_BASENAME.tar.xz"
-tar xf "$CACHE_BASENAME.tar.xz"
-
-ZIG="$PREFIX/bin/zig"
-
-cd $ZIGDIR
-
-# Make the `zig version` number consistent.
-# This will affect the cmake command below.
-git fetch --unshallow || true
-git fetch --tags
-
-# Test building from source without LLVM.
-git clean -fd
-rm -rf zig-out
-cc -o bootstrap bootstrap.c
-./bootstrap
-./zig2 build -Dno-lib
-./zig-out/bin/zig test test/behavior.zig
-
-rm -rf build
-mkdir build
-cd build
-
-# Override the cache directories because they won't actually help other CI runs
-# which will be testing alternate versions of zig, and ultimately would just
-# fill up space on the hard drive for no reason.
-export ZIG_GLOBAL_CACHE_DIR="$PWD/zig-global-cache"
-export ZIG_LOCAL_CACHE_DIR="$PWD/zig-local-cache"
-
-cmake .. \
-  -DCMAKE_PREFIX_PATH="$PREFIX" \
-  -DCMAKE_BUILD_TYPE=Release \
-  -DCMAKE_C_COMPILER="$ZIG;cc;-target;$TARGET;-mcpu=$MCPU" \
-  -DCMAKE_CXX_COMPILER="$ZIG;c++;-target;$TARGET;-mcpu=$MCPU" \
-  -DZIG_TARGET_TRIPLE="$TARGET" \
-  -DZIG_TARGET_MCPU="$MCPU" \
-  -DZIG_STATIC=ON \
-  -DZIG_NO_LIB=ON
-
-make $JOBS install
-
-stage3/bin/zig build test docs \
-  --zig-lib-dir "$PWD/../lib" \
-  -Denable-macos-sdk \
-  -Dstatic-llvm \
-  -Dskip-non-native \
-  --search-prefix "$PREFIX"
-
-# Ensure that stage3 and stage4 are byte-for-byte identical.
-stage3/bin/zig build \
-  --prefix stage4 \
-  -Denable-llvm \
-  -Dno-lib \
-  -Doptimize=ReleaseFast \
-  -Dstrip \
-  -Dtarget=$TARGET \
-  -Duse-zig-libcxx \
-  -Dversion-string="$(stage3/bin/zig version)"
-
-# diff returns an error code if the files differ.
-echo "If the following command fails, it means nondeterminism has been"
-echo "introduced, making stage3 and stage4 no longer byte-for-byte identical."
-diff stage3/bin/zig stage4/bin/zig
diff --git a/ci/x86_64-windows-debug.ps1 b/ci/x86_64-windows-debug.ps1
deleted file mode 100644
index 6f8039883df4..000000000000
--- a/ci/x86_64-windows-debug.ps1
+++ /dev/null
@@ -1,94 +0,0 @@
-$TARGET = "$($Env:ARCH)-windows-gnu"
-$ZIG_LLVM_CLANG_LLD_NAME = "zig+llvm+lld+clang-$TARGET-0.12.0-dev.2073+402fe565a"
-$MCPU = "baseline"
-$PREFIX_PATH = "$($Env:USERPROFILE)\$ZIG_LLVM_CLANG_LLD_NAME"
-$ZIG = "$PREFIX_PATH\bin\zig.exe"
-$ZIG_LIB_DIR = "$(Get-Location)\lib"
-
-function CheckLastExitCode {
-    if (!$?) {
-        exit 1
-    }
-    return 0
-}
-
-# Make the `zig version` number consistent.
-# This will affect the `zig build` command below which uses `git describe`.
-git fetch --tags
-
-if ((git rev-parse --is-shallow-repository) -eq "true") {
-    git fetch --unshallow # `git describe` won't work on a shallow repo
-}
-
-Write-Output "Building from source..."
-Remove-Item -Path 'build-debug' -Recurse -Force -ErrorAction Ignore
-New-Item -Path 'build-debug' -ItemType Directory
-Set-Location -Path 'build-debug'
-
-# CMake gives a syntax error when file paths with backward slashes are used.
-# Here, we use forward slashes only to work around this.
-& cmake .. `
-  -GNinja `
-  -DCMAKE_INSTALL_PREFIX="stage3-debug" `
-  -DCMAKE_PREFIX_PATH="$($PREFIX_PATH -Replace "\\", "/")" `
-  -DCMAKE_BUILD_TYPE=Debug `
-  -DCMAKE_C_COMPILER="$($ZIG -Replace "\\", "/");cc;-target;$TARGET;-mcpu=$MCPU" `
-  -DCMAKE_CXX_COMPILER="$($ZIG -Replace "\\", "/");c++;-target;$TARGET;-mcpu=$MCPU" `
-  -DCMAKE_AR="$($ZIG -Replace "\\", "/")" `
-  -DZIG_AR_WORKAROUND=ON `
-  -DZIG_TARGET_TRIPLE="$TARGET" `
-  -DZIG_TARGET_MCPU="$MCPU" `
-  -DZIG_STATIC=ON `
-  -DZIG_NO_LIB=ON
-CheckLastExitCode
-
-ninja install
-CheckLastExitCode
-
-Write-Output "Main test suite..."
-& "stage3-debug\bin\zig.exe" build test docs `
-  --zig-lib-dir "$ZIG_LIB_DIR" `
-  --search-prefix "$PREFIX_PATH" `
-  -Dstatic-llvm `
-  -Dskip-non-native `
-  -Dskip-release `
-  -Denable-symlinks-windows
-CheckLastExitCode
-
-Write-Output "Build x86_64-windows-msvc behavior tests using the C backend..."
-& "stage3-debug\bin\zig.exe" test `
-  ..\test\behavior.zig `
-  --zig-lib-dir "$ZIG_LIB_DIR" `
-  -ofmt=c `
-  -femit-bin="test-x86_64-windows-msvc.c" `
-  --test-no-exec `
-  -target x86_64-windows-msvc `
-  -lc
-CheckLastExitCode
-
-& "stage3-debug\bin\zig.exe" build-obj `
-  --zig-lib-dir "$ZIG_LIB_DIR" `
-  -ofmt=c `
-  -OReleaseSmall `
-  --name compiler_rt `
-  -femit-bin="compiler_rt-x86_64-windows-msvc.c" `
-  --dep build_options `
-  -target x86_64-windows-msvc `
-  --mod root ..\lib\compiler_rt.zig `
-  --mod build_options config.zig
-CheckLastExitCode
-
-Import-Module "C:\Program Files (x86)\Microsoft Visual Studio\2022\BuildTools\Common7\Tools\Microsoft.VisualStudio.DevShell.dll"
-CheckLastExitCode
-
-Enter-VsDevShell -VsInstallPath "C:\Program Files (x86)\Microsoft Visual Studio\2022\BuildTools" `
-  -DevCmdArguments '-arch=x64 -no_logo' `
-  -StartInPath $(Get-Location)
-CheckLastExitCode
-
-Write-Output "Build and run behavior tests with msvc..."
-& cl.exe -I..\lib test-x86_64-windows-msvc.c compiler_rt-x86_64-windows-msvc.c /W3 /Z7 -link -nologo -debug -subsystem:console kernel32.lib ntdll.lib libcmt.lib
-CheckLastExitCode
-
-& .\test-x86_64-windows-msvc.exe
-CheckLastExitCode
diff --git a/ci/x86_64-windows-release.ps1 b/ci/x86_64-windows-release.ps1
deleted file mode 100644
index 68d22c9eaba0..000000000000
--- a/ci/x86_64-windows-release.ps1
+++ /dev/null
@@ -1,93 +0,0 @@
-$TARGET = "$($Env:ARCH)-windows-gnu"
-$ZIG_LLVM_CLANG_LLD_NAME = "zig+llvm+lld+clang-$TARGET-0.12.0-dev.2073+402fe565a"
-$MCPU = "baseline"
-$PREFIX_PATH = "$($Env:USERPROFILE)\$ZIG_LLVM_CLANG_LLD_NAME"
-$ZIG = "$PREFIX_PATH\bin\zig.exe"
-$ZIG_LIB_DIR = "$(Get-Location)\lib"
-
-function CheckLastExitCode {
-    if (!$?) {
-        exit 1
-    }
-    return 0
-}
-
-# Make the `zig version` number consistent.
-# This will affect the `zig build` command below which uses `git describe`.
-git fetch --tags
-
-if ((git rev-parse --is-shallow-repository) -eq "true") {
-    git fetch --unshallow # `git describe` won't work on a shallow repo
-}
-
-Write-Output "Building from source..."
-Remove-Item -Path 'build-release' -Recurse -Force -ErrorAction Ignore
-New-Item -Path 'build-release' -ItemType Directory
-Set-Location -Path 'build-release'
-
-# CMake gives a syntax error when file paths with backward slashes are used.
-# Here, we use forward slashes only to work around this.
-& cmake .. `
-  -GNinja `
-  -DCMAKE_INSTALL_PREFIX="stage3-release" `
-  -DCMAKE_PREFIX_PATH="$($PREFIX_PATH -Replace "\\", "/")" `
-  -DCMAKE_BUILD_TYPE=Release `
-  -DCMAKE_C_COMPILER="$($ZIG -Replace "\\", "/");cc;-target;$TARGET;-mcpu=$MCPU" `
-  -DCMAKE_CXX_COMPILER="$($ZIG -Replace "\\", "/");c++;-target;$TARGET;-mcpu=$MCPU" `
-  -DCMAKE_AR="$($ZIG -Replace "\\", "/")" `
-  -DZIG_AR_WORKAROUND=ON `
-  -DZIG_TARGET_TRIPLE="$TARGET" `
-  -DZIG_TARGET_MCPU="$MCPU" `
-  -DZIG_STATIC=ON `
-  -DZIG_NO_LIB=ON
-CheckLastExitCode
-
-ninja install
-CheckLastExitCode
-
-Write-Output "Main test suite..."
-& "stage3-release\bin\zig.exe" build test docs `
-  --zig-lib-dir "$ZIG_LIB_DIR" `
-  --search-prefix "$PREFIX_PATH" `
-  -Dstatic-llvm `
-  -Dskip-non-native `
-  -Denable-symlinks-windows
-CheckLastExitCode
-
-Write-Output "Build x86_64-windows-msvc behavior tests using the C backend..."
-& "stage3-release\bin\zig.exe" test `
-  ..\test\behavior.zig `
-  --zig-lib-dir "$ZIG_LIB_DIR" `
-  -ofmt=c `
-  -femit-bin="test-x86_64-windows-msvc.c" `
-  --test-no-exec `
-  -target x86_64-windows-msvc `
-  -lc
-CheckLastExitCode
-
-& "stage3-release\bin\zig.exe" build-obj `
-  --zig-lib-dir "$ZIG_LIB_DIR" `
-  -ofmt=c `
-  -OReleaseSmall `
-  --name compiler_rt `
-  -femit-bin="compiler_rt-x86_64-windows-msvc.c" `
-  --dep build_options `
-  -target x86_64-windows-msvc `
-  --mod root ..\lib\compiler_rt.zig `
-  --mod build_options config.zig
-CheckLastExitCode
-
-Import-Module "C:\Program Files (x86)\Microsoft Visual Studio\2022\BuildTools\Common7\Tools\Microsoft.VisualStudio.DevShell.dll"
-CheckLastExitCode
-
-Enter-VsDevShell -VsInstallPath "C:\Program Files (x86)\Microsoft Visual Studio\2022\BuildTools" `
-  -DevCmdArguments '-arch=x64 -no_logo' `
-  -StartInPath $(Get-Location)
-CheckLastExitCode
-
-Write-Output "Build and run behavior tests with msvc..."
-& cl.exe -I..\lib test-x86_64-windows-msvc.c compiler_rt-x86_64-windows-msvc.c /W3 /Z7 -link -nologo -debug -subsystem:console kernel32.lib ntdll.lib libcmt.lib
-CheckLastExitCode
-
-& .\test-x86_64-windows-msvc.exe
-CheckLastExitCode
diff --git a/lib/std/Build/Step/RemoveDir.zig b/lib/std/Build/Step/RemoveDir.zig
index 64a3c72668ee..4ce755e11885 100644
--- a/lib/std/Build/Step/RemoveDir.zig
+++ b/lib/std/Build/Step/RemoveDir.zig
@@ -31,14 +31,8 @@ fn make(step: *Step, prog_node: *std.Progress.Node) !void {
     const remove_dir: *RemoveDir = @fieldParentPtr("step", step);
 
     b.build_root.handle.deleteTree(remove_dir.dir_path) catch |err| {
-        if (b.build_root.path) |base| {
-            return step.fail("unable to recursively delete path '{s}/{s}': {s}", .{
-                base, remove_dir.dir_path, @errorName(err),
-            });
-        } else {
-            return step.fail("unable to recursively delete path '{s}': {s}", .{
-                remove_dir.dir_path, @errorName(err),
-            });
-        }
+        return step.fail("unable to recursively delete path '{s}': {s}", .{
+            b.pathFromRoot(remove_dir.dir_path), @errorName(err),
+        });
     };
 }
diff --git a/lib/std/posix.zig b/lib/std/posix.zig
index c3dbed2c61fb..a37cdf82d522 100644
--- a/lib/std/posix.zig
+++ b/lib/std/posix.zig
@@ -7298,7 +7298,10 @@ const lfs64_abi = native_os == .linux and builtin.link_libc and builtin.abi.isGn
 /// If this happens the fix is to add the error code to the corresponding
 /// switch expression, possibly introduce a new error in the error set, and
 /// send a patch to Zig.
-pub const unexpected_error_tracing = builtin.zig_backend == .stage2_llvm and builtin.mode == .Debug;
+pub const unexpected_error_tracing = switch (builtin.zig_backend) {
+    .stage2_c, .stage2_llvm, .stage2_x86_64 => true,
+    else => false,
+};
 
 pub const UnexpectedError = error{
     /// The Operating System returned an undocumented error code.