diff --git a/build_tools/scripts/byo_llvm.sh b/build_tools/scripts/byo_llvm.sh
new file mode 100755
index 0000000..e833311
--- /dev/null
+++ b/build_tools/scripts/byo_llvm.sh
@@ -0,0 +1,195 @@
+#!/usr/bin/env bash
+# Copyright 2023 The IREE Authors
+#
+# Licensed under the Apache License v2.0 with LLVM Exceptions.
+# See https://llvm.org/LICENSE.txt for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+# This script illustrates how IREE can be built with various forms of LLVM
+# installations with the option -DIREE_BUILD_BUNDLED_LLVM=OFF set, disabling
+# a source dependency on the bundled LLVM submodule.
+#
+# Usage:
+#   byo_llvm.sh build_llvm && \
+#   byo_llvm.sh build_mlir && \
+#   byo_llvm.sh build_iree
+#
+# This script has minimal configurability, which can be extended as needed. The
+# defaults should suffice for testing on CI. Different configurations are
+# possible (i.e. building MLIR bundled with LLVM vs standalone), and this
+# is just normal CMake package management options.
+#
+# Fully separating LLVM+LLD+CLANG from MLIR and from IREE enables maximum
+# flexibility for the cases where multiple teams are responsible for
+# different parts. Note that IREE often has a tight dependency on specific
+# MLIR commits, and the bundled submodule often carries patches and fixes
+# required for full functionality of all backends.
+
+TD="$(cd $(dirname $0) && pwd)"
+REPO_ROOT="$(cd $TD/../.. && pwd)"
+LLVM_SOURCE_DIR="${LLVM_SOURCE_DIR:-${REPO_ROOT}/third_party/llvm-project}"
+LLVM_BUILD_DIR="${LLVM_BUILD_DIR:-${REPO_ROOT}/../iree-llvm-build}"
+LLVM_INSTALL_DIR="${LLVM_INSTALL_DIR:-${REPO_ROOT}/../iree-llvm-install}"
+
+command="$1"
+shift
+
+# Detect commands.
+has_ccache=false
+if (command -v ccache &> /dev/null); then
+  has_ccache=true
+fi
+has_clang=false
+if (command -v clang &> /dev/null) && (command -v clang++ &> /dev/null); then
+  has_clang=true
+fi
+has_lld=false
+if (command -v lld &> /dev/null); then
+  has_lld=true
+fi
+python3_command=""
+if (command -v python3 &> /dev/null); then
+  python3_command="python3"
+elif (command -v python &> /dev/null); then
+  python3_command="python"
+fi
+
+set -euo pipefail
+
+print_toolchain_config() {
+  if $has_ccache; then
+    echo -n "-DCMAKE_C_COMPILER_LAUNCHER=ccache -DCMAKE_CXX_COMPILER_LAUNCHER=ccache "
+  fi
+  if $has_clang; then
+    echo "-DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++"
+  fi
+}
+
+do_build_llvm() {
+  echo "*********************** BUILDING LLVM *********************************"
+  main_build_dir="${LLVM_BUILD_DIR}/llvm"
+  main_install_dir="${LLVM_INSTALL_DIR}/llvm"
+  targets_to_build="${LLVM_TARGETS_TO_BUILD:-X86}"
+  enable_projects="${LLVM_ENABLE_TARGETS:-clang;lld}"
+
+  cmake_options="-DLLVM_ENABLE_PROJECTS='${enable_projects}' -DLLVM_TARGETS_TO_BUILD='${targets_to_build}'"
+  cmake_options="${cmake_options} -DLLVM_BUILD_EXAMPLES=OFF"
+  cmake_options="${cmake_options} -DLLVM_INSTALL_UTILS=ON"
+  cmake_options="${cmake_options} -DCMAKE_BUILD_TYPE=Release"
+  cmake_options="${cmake_options} -DLLVM_ENABLE_ASSERTIONS=ON"
+  cmake_options="${cmake_options} $(print_toolchain_config)"
+  if $has_lld; then
+    cmake_options="${cmake_options} -DLLVM_ENABLE_LLD=ON"
+  fi
+
+  echo "Source Directory: ${LLVM_SOURCE_DIR}"
+  echo "Build Directory: ${main_build_dir}"
+  echo "CMake Options: ${cmake_options}"
+  cmake -GNinja -S "${LLVM_SOURCE_DIR}/llvm" -B "${main_build_dir}" \
+    $cmake_options
+  cmake --build "${main_build_dir}"
+  cmake -DCMAKE_INSTALL_PREFIX="${main_install_dir}" -P "${main_build_dir}/cmake_install.cmake"
+}
+
+do_build_mlir() {
+  echo "*********************** BUILDING MLIR *********************************"
+  main_install_dir="${LLVM_INSTALL_DIR}/llvm"
+  mlir_build_dir="${LLVM_BUILD_DIR}/mlir"
+  mlir_install_dir="${LLVM_INSTALL_DIR}/mlir"
+
+  cmake_options="-DLLVM_DIR='${main_install_dir}/lib/cmake/llvm'"
+  cmake_options="${cmake_options} -DPython3_EXECUTABLE='$(which $python3_command)'"
+  cmake_options="${cmake_options} -DLLVM_INSTALL_TOOLCHAIN_ONLY=OFF"
+  cmake_options="${cmake_options} -DLLVM_BUILD_TOOLS=ON"
+  cmake_options="${cmake_options} -DLLVM_ENABLE_ASSERTIONS=ON"
+  cmake_options="${cmake_options} -DMLIR_ENABLE_BINDINGS_PYTHON=ON"
+  cmake_options="${cmake_options} $(print_toolchain_config)"
+  if $has_lld; then
+    cmake_options="${cmake_options} -DLLVM_ENABLE_LLD=ON"
+  fi
+
+  echo "Source Directory: ${LLVM_SOURCE_DIR}"
+  echo "Build Directory: ${mlir_build_dir}"
+  echo "CMake Options: ${cmake_options}"
+  cmake -GNinja -S "${LLVM_SOURCE_DIR}/mlir" -B "${mlir_build_dir}" \
+    $cmake_options
+  cmake --build "${mlir_build_dir}"
+  cmake -DCMAKE_INSTALL_PREFIX="${mlir_install_dir}" -P "${mlir_build_dir}/cmake_install.cmake"
+}
+
+print_iree_config() {
+  llvm_cmake_dir="${LLVM_INSTALL_DIR}/llvm/lib/cmake/llvm"
+  lld_cmake_dir="${LLVM_INSTALL_DIR}/llvm/lib/cmake/lld"
+  clang_cmake_dir="${LLVM_INSTALL_DIR}/llvm/lib/cmake/clang"
+  # TODO: There seem to be utility exports missing from installed MLIR,
+  # so using the build tree for now. This isn't great but needs fixing
+  # upstream.
+  #mlir_cmake_dir="${LLVM_INSTALL_DIR}/mlir/lib/cmake/mlir"
+  mlir_cmake_dir="${LLVM_BUILD_DIR}/mlir/lib/cmake/mlir"
+
+  if ! [ -d "$llvm_cmake_dir" ]; then
+    echo "WARNING: CMake dir does not exist ($llvm_cmake_dir)" >&2
+    return 1
+  fi
+  if ! [ -d "$lld_cmake_dir" ]; then
+    echo "WARNING: CMake dir does not exist ($lld_cmake_dir)" >&2
+    return 1
+  fi
+  if ! [ -d "$clang_cmake_dir" ]; then
+    echo "WARNING: CMake dir does not exist ($clang_cmake_dir)" >&2
+    return 1
+  fi
+  if ! [ -d "$mlir_cmake_dir" ]; then
+    echo "WARNING: CMake dir does not exist ($mlir_cmake_dir)" >&2
+    return 1
+  fi
+
+  echo "-DLLVM_DIR='$llvm_cmake_dir' -DLLD_DIR='$lld_cmake_dir' -DCLANG_DIR='$clang_cmake_dir' -DMLIR_DIR='$mlir_cmake_dir' -DIREE_BUILD_BUNDLED_LLVM=OFF"
+}
+
+do_build_iree() {
+  echo "*********************** BUILDING IREE *********************************"
+  iree_build_dir="${LLVM_BUILD_DIR}/iree"
+  iree_install_dir="${LLVM_INSTALL_DIR}/iree"
+
+  cmake_options="$(print_iree_config)"
+  cmake_options="${cmake_options} -DPython3_EXECUTABLE='$(which $python3_command)'"
+  cmake_options="${cmake_options} -DIREE_BUILD_PYTHON_BINDINGS=ON"
+  cmake_options="${cmake_options} -DIREE_TARGET_BACKEND_DEFAULTS=OFF"
+  cmake_options="${cmake_options} -DIREE_HAL_DRIVER_DEFAULTS=OFF"
+  cmake_options="${cmake_options} -DIREE_HAL_DRIVER_LOCAL_SYNC=ON"
+  cmake_options="${cmake_options} -DIREE_HAL_DRIVER_LOCAL_TASK=ON"
+  cmake_options="${cmake_options} -DCMAKE_BUILD_TYPE=Release"
+  cmake_options="${cmake_options} -DIREE_ENABLE_ASSERTIONS=ON"
+  cmake_options="${cmake_options} $(print_toolchain_config)"
+  if $has_lld; then
+    cmake_options="${cmake_options} -DIREE_ENABLE_LLD=ON"
+  fi
+
+  echo "Source Directory: ${REPO_ROOT}"
+  echo "Build Directory: ${iree_build_dir}"
+  echo "CMake Options: ${cmake_options}"
+  cmake -GNinja -S "${REPO_ROOT}" -B "${iree_build_dir}" \
+    $cmake_options
+  cmake --build "${iree_build_dir}"
+  cmake -DCMAKE_INSTALL_PREFIX="${iree_install_dir}" -P "${iree_build_dir}/cmake_install.cmake"
+}
+
+case "${command}" in
+  build_llvm)
+    do_build_llvm
+    ;;
+
+  build_mlir)
+    do_build_mlir
+    ;;
+
+  build_iree)
+    do_build_iree
+    ;;
+
+  *)
+    echo "ERROR: Expected command of 'build_llvm', 'clean_install' (got '${command}')"
+    exit 1
+    ;;
+esac