diff --git a/build/Test.cmake b/build/Test.cmake
index 31e5aaf4d63..dbe590d610b 100644
--- a/build/Test.cmake
+++ b/build/Test.cmake
@@ -36,6 +36,7 @@ function(et_cxx_test target_name)
   cmake_parse_arguments(ET_CXX_TEST "" "" "${multi_arg_names}" ${ARGN})
 
   add_executable(${target_name} ${ET_CXX_TEST_SOURCES} ${EXECUTORCH_ROOT}/runtime/core/exec_aten/testing_util/tensor_util.cpp)
+  find_package(GTest)
   # Includes gtest, gmock, executorch by default
   target_link_libraries(
     ${target_name} GTest::gtest GTest::gtest_main GTest::gmock executorch
diff --git a/build/Utils.cmake b/build/Utils.cmake
index 646ef5ff285..6e7459430b7 100644
--- a/build/Utils.cmake
+++ b/build/Utils.cmake
@@ -329,29 +329,25 @@ function(resolve_python_executable)
 endfunction()
 
 # find_package(Torch CONFIG REQUIRED) replacement for targets that have a
-# header-only Torch dependency. Because find_package sets variables in the
-# parent scope, we use a macro to preserve this rather than maintaining our own
-# list of those variables.
-macro(find_package_torch_headers)
-  # We cannot simply use CMAKE_FIND_ROOT_PATH_BOTH, because that does not
-  # propagate into TorchConfig.cmake.
-  foreach(mode_kind IN ITEMS PACKAGE LIBRARY INCLUDE)
-    set(OLD_CMAKE_FIND_ROOT_PATH_MODE_${mode_kind}
-        ${CMAKE_FIND_ROOT_PATH_MODE_${mode_kind}}
-    )
-    set(CMAKE_FIND_ROOT_PATH_MODE_${mode_kind} BOTH)
-  endforeach()
-  find_package_torch()
-  foreach(mode_kind IN ITEMS PACKAGE LIBRARY INCLUDE)
-    set(CMAKE_FIND_ROOT_PATH_MODE_${mode_kind}
-        ${OLD_CMAKE_FIND_ROOT_PATH_MODE_${mode_kind}}
-    )
-  endforeach()
-endmacro()
+# header-only Torch dependency.
+#
+# Unlike find_package(Torch ...), this will only set
+# TORCH_INCLUDE_DIRS in the parent scope. In particular, it will NOT
+# set any of the following:
+# - TORCH_FOUND
+# - TORCH_LIBRARY
+# - TORCH_CXX_FLAGS
+function(find_package_torch_headers)
+  # We implement this way rather than using find_package so that
+  # cross-compilation can still use the host's installed copy of
+  # torch, since the headers should be fine.
+  get_torch_base_path(TORCH_BASE_PATH)
+  set(TORCH_INCLUDE_DIRS "${TORCH_BASE_PATH}/include;${TORCH_BASE_PATH}/include/torch/csrc/api/include" PARENT_SCOPE)
+endfunction()
 
-# Add the Torch CMake configuration to CMAKE_PREFIX_PATH so that find_package
-# can find Torch.
-function(add_torch_to_cmake_prefix_path)
+# Return the base path to the installed Torch Python library in
+# outVar.
+function(get_torch_base_path outVar)
   if(NOT PYTHON_EXECUTABLE)
     resolve_python_executable()
   endif()
@@ -370,6 +366,13 @@ function(add_torch_to_cmake_prefix_path)
     message("Output:\n${_tmp_torch_path}")
     message(FATAL_ERROR "Error:\n${_tmp_torch_path_error}")
   endif()
+  set(${outVar} ${_tmp_torch_path} PARENT_SCOPE)
+endfunction()
+
+# Add the Torch CMake configuration to CMAKE_PREFIX_PATH so that find_package
+# can find Torch.
+function(add_torch_to_cmake_prefix_path)
+  get_torch_base_path(_tmp_torch_path)
   list(APPEND CMAKE_PREFIX_PATH "${_tmp_torch_path}")
   set(CMAKE_PREFIX_PATH
       "${CMAKE_PREFIX_PATH}"
diff --git a/build/build_android_llm_demo.sh b/build/build_android_llm_demo.sh
index 4119bde4c7e..cb2d47fdeb3 100644
--- a/build/build_android_llm_demo.sh
+++ b/build/build_android_llm_demo.sh
@@ -44,6 +44,7 @@ build_android_native_library() {
     -DCMAKE_TOOLCHAIN_FILE="${ANDROID_NDK}/build/cmake/android.toolchain.cmake" \
     -DANDROID_ABI="${ANDROID_ABI}" \
     -DANDROID_PLATFORM=android-26 \
+    -DBUILD_TESTING=OFF \
     -DEXECUTORCH_ENABLE_LOGGING=ON \
     -DEXECUTORCH_LOG_LEVEL=Info \
     -DEXECUTORCH_BUILD_XNNPACK=ON \
@@ -73,6 +74,7 @@ build_android_native_library() {
     -DCMAKE_TOOLCHAIN_FILE=${ANDROID_NDK}/build/cmake/android.toolchain.cmake \
     -DANDROID_ABI="${ANDROID_ABI}" \
     -DANDROID_PLATFORM=android-26 \
+    -DBUILD_TESTING=OFF \
     -DCMAKE_INSTALL_PREFIX="${CMAKE_OUT}" \
     -DEXECUTORCH_ENABLE_LOGGING=ON \
     -DEXECUTORCH_LOG_LEVEL=Info \
diff --git a/extension/android_test/setup.sh b/extension/android_test/setup.sh
index 725728b8092..c21d2c09623 100755
--- a/extension/android_test/setup.sh
+++ b/extension/android_test/setup.sh
@@ -21,6 +21,7 @@ build_native_library() {
   cmake . -DCMAKE_INSTALL_PREFIX="${CMAKE_OUT}" \
     -DCMAKE_TOOLCHAIN_FILE="${ANDROID_NDK}/build/cmake/android.toolchain.cmake" \
     -DANDROID_ABI="${ANDROID_ABI}" \
+    -DBUILD_TESTING=OFF \
     -DEXECUTORCH_BUILD_XNNPACK=ON \
     -DEXECUTORCH_XNNPACK_SHARED_WORKSPACE=ON \
     -DEXECUTORCH_BUILD_EXTENSION_DATA_LOADER=ON \
@@ -36,6 +37,7 @@ build_native_library() {
   cmake extension/android \
     -DCMAKE_TOOLCHAIN_FILE="${ANDROID_NDK}"/build/cmake/android.toolchain.cmake \
     -DANDROID_ABI="${ANDROID_ABI}" \
+    -DBUILD_TESTING=OFF \
     -DCMAKE_INSTALL_PREFIX=c"${CMAKE_OUT}" \
     -DEXECUTORCH_BUILD_KERNELS_CUSTOM=ON \
     -DEXECUTORCH_BUILD_LLAMA_JNI=ON \
diff --git a/extension/llm/custom_ops/CMakeLists.txt b/extension/llm/custom_ops/CMakeLists.txt
index 95f4bc559fa..da00320a89f 100644
--- a/extension/llm/custom_ops/CMakeLists.txt
+++ b/extension/llm/custom_ops/CMakeLists.txt
@@ -121,3 +121,8 @@ if(EXECUTORCH_BUILD_KERNELS_CUSTOM_AOT)
           LIBRARY DESTINATION executorch/extension/llm/custom_ops
   )
 endif()
+
+add_subdirectory(spinquant/third-party/FFHT)
+if(BUILD_TESTING)
+  add_subdirectory(spinquant/test)
+endif()
diff --git a/extension/llm/custom_ops/spinquant/test/CMakeLists.txt b/extension/llm/custom_ops/spinquant/test/CMakeLists.txt
new file mode 100644
index 00000000000..c793d2ed975
--- /dev/null
+++ b/extension/llm/custom_ops/spinquant/test/CMakeLists.txt
@@ -0,0 +1,30 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree.
+
+# @generated by test/utils/generate_gtest_cmakelists.py
+#
+# This file should be formatted with
+# ~~~
+# cmake-format -i CMakeLists.txt
+# ~~~
+# It should also be cmake-lint clean.
+#
+
+cmake_minimum_required(VERSION 3.19)
+
+set(EXECUTORCH_ROOT ${CMAKE_CURRENT_SOURCE_DIR}/../../../../..)
+
+include(${EXECUTORCH_ROOT}/build/Test.cmake)
+
+set(_test_srcs
+    fast_hadamard_transform_test.cpp fast_hadamard_transform_test_impl.cpp
+    op_fast_hadamard_transform_test.cpp
+)
+
+et_cxx_test(
+  extension_llm_custom_ops_spinquant_test SOURCES ${_test_srcs} EXTRA_LIBS
+  custom_ops dumb_fht
+)
diff --git a/extension/llm/custom_ops/spinquant/third-party/FFHT/CMakeLists.txt b/extension/llm/custom_ops/spinquant/third-party/FFHT/CMakeLists.txt
new file mode 100644
index 00000000000..2e3089be72e
--- /dev/null
+++ b/extension/llm/custom_ops/spinquant/third-party/FFHT/CMakeLists.txt
@@ -0,0 +1,12 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree.
+
+# Please this file formatted by running:
+# ~~~
+# cmake-format -i CMakeLists.txt
+# ~~~
+
+add_library(dumb_fht dumb_fht.c)
diff --git a/test/run_oss_cpp_tests.sh b/test/run_oss_cpp_tests.sh
index f747100006d..ff2ed048257 100755
--- a/test/run_oss_cpp_tests.sh
+++ b/test/run_oss_cpp_tests.sh
@@ -35,6 +35,7 @@ build_executorch() {
   cmake . \
     -DCMAKE_INSTALL_PREFIX=cmake-out \
     -DEXECUTORCH_USE_CPP_CODE_COVERAGE=ON \
+    -DEXECUTORCH_BUILD_KERNELS_CUSTOM=ON \
     -DEXECUTORCH_BUILD_KERNELS_OPTIMIZED=ON \
     -DEXECUTORCH_BUILD_KERNELS_QUANTIZED=ON \
     -DEXECUTORCH_BUILD_EXTENSION_DATA_LOADER=ON \
diff --git a/test/utils/OSSTestConfig.json b/test/utils/OSSTestConfig.json
index 6eff74eec86..70cb2d2e44f 100644
--- a/test/utils/OSSTestConfig.json
+++ b/test/utils/OSSTestConfig.json
@@ -1,4 +1,15 @@
 { "tests": [
+    {
+        "directory": "extension/llm/custom_ops/spinquant/test",
+        "sources": [
+            "fast_hadamard_transform_test.cpp",
+            "fast_hadamard_transform_test_impl.cpp",
+            "op_fast_hadamard_transform_test.cpp"
+        ],
+        "additional_libs": [
+            "custom_ops"
+        ]
+    },
     {
         "directory": "extension/data_loader/test",
         "sources": [