pytorch · metascroy · Jan 20, 2026
@@ -48,6 +48,13 @@
 # TODO Lower to 3.24 when XNNPACK dependency is updated to include
 # https://github.com/google/XNNPACK/commit/c690daa67f883e1b627aadf7684c06797e9a0684
 cmake_minimum_required(VERSION 3.29)
+
+# Set minimum macOS deployment target for Apple platforms.
+# This must be set before the project() call and before any subdirectory processing.
+# MLX requires macOS >= 14.0, so we default to 14.0 if not set.
+if(APPLE AND (NOT CMAKE_OSX_DEPLOYMENT_TARGET OR CMAKE_OSX_DEPLOYMENT_TARGET STREQUAL ""))
+  set(CMAKE_OSX_DEPLOYMENT_TARGET "14.0" CACHE STRING "Minimum macOS version" FORCE)
+endif()
 project(executorch)
 
 set(EXECUTORCH_ROOT ${CMAKE_CURRENT_SOURCE_DIR})
@@ -563,6 +570,11 @@ if(EXECUTORCH_BUILD_MPS)
   list(APPEND _executorch_backends mpsdelegate)
 endif()
 
+if(EXECUTORCH_BUILD_MLX)
+  add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/backends/apple/mlx)
+  list(APPEND _executorch_backends mlxdelegate)
+endif()
+
 if(EXECUTORCH_BUILD_NEURON)
   add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/backends/mediatek)
   list(APPEND _executorch_backends neuron_backend)
@@ -842,6 +854,10 @@ if(EXECUTORCH_BUILD_PYBIND)
     list(APPEND _dep_libs mpsdelegate)
   endif()
 
+  if(EXECUTORCH_BUILD_MLX)
+    list(APPEND _dep_libs mlxdelegate)
+  endif()
+
   if(EXECUTORCH_BUILD_OPENVINO)
     list(APPEND _dep_libs openvino_backend)
   endif()

@@ -110,7 +110,7 @@
       "inherits": ["common"],
       "cacheVariables": {
         "EXECUTORCH_BUILD_PRESET_FILE": "${sourceDir}/tools/cmake/preset/pybind.cmake",
-        "CMAKE_OSX_DEPLOYMENT_TARGET": "12.0"
+        "CMAKE_OSX_DEPLOYMENT_TARGET": "14.0"
       },
       "condition": {
         "type": "inList",

@@ -0,0 +1,147 @@
+#
+# 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.
+#
+
+cmake_minimum_required(VERSION 3.19)
+
+set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
+
+if(NOT CMAKE_CXX_STANDARD)
+  set(CMAKE_CXX_STANDARD 17)
+endif()
+
+# Source root directory for executorch.
+if(NOT EXECUTORCH_ROOT)
+  set(EXECUTORCH_ROOT ${CMAKE_CURRENT_SOURCE_DIR}/../../..)
+endif()
+
+include(${EXECUTORCH_ROOT}/tools/cmake/Utils.cmake)
+
+set(_common_compile_options -Wno-deprecated-declarations)
+
+# -----------------------------------------------------------------------------
+# FlatBuffer schema generation
+# -----------------------------------------------------------------------------
+
+set(_mlx_schema__include_dir "${CMAKE_BINARY_DIR}/schema/include")
+set(_mlx_schema__srcs
+    ${CMAKE_CURRENT_SOURCE_DIR}/serialization/schema.fbs
+)
+
+# Paths to headers generated from the .fbs files.
+set(_mlx_schema__outputs
+    "${_mlx_schema__include_dir}/executorch/backends/apple/mlx/serialization/schema_generated.h"
+)
+
+# Generate the headers from the .fbs files.
+add_custom_command(
+  OUTPUT ${_mlx_schema__outputs}
+  COMMAND
+    flatc --cpp --cpp-std c++11 --scoped-enums -o
+    "${_mlx_schema__include_dir}/executorch/backends/apple/mlx/serialization"
+    ${_mlx_schema__srcs}
+  WORKING_DIRECTORY ${EXECUTORCH_ROOT}
+  DEPENDS flatc ${_mlx_schema__srcs}
+  COMMENT "Generating mlx_schema headers"
+  VERBATIM
+)
+
+add_library(mlx_schema INTERFACE ${_mlx_schema__outputs})
+set_target_properties(mlx_schema PROPERTIES LINKER_LANGUAGE CXX)
+target_include_directories(
+  mlx_schema
+  INTERFACE
+    $<BUILD_INTERFACE:${_mlx_schema__include_dir}>
+    $<BUILD_INTERFACE:${EXECUTORCH_ROOT}/third-party/flatbuffers/include>
+)
+
+# -----------------------------------------------------------------------------
+# MLX dependency (fetched via FetchContent)
+# -----------------------------------------------------------------------------
+
+include(FetchContent)
+
+# MLX build options - we only need the C++ library
+set(MLX_BUILD_PYTHON_BINDINGS OFF CACHE BOOL "" FORCE)
+set(MLX_BUILD_TESTS OFF CACHE BOOL "" FORCE)
+set(MLX_BUILD_EXAMPLES OFF CACHE BOOL "" FORCE)
+set(MLX_BUILD_BENCHMARKS OFF CACHE BOOL "" FORCE)
+set(MLX_BUILD_CPU OFF CACHE BOOL "" FORCE)
+set(MLX_BUILD_METAL ON CACHE BOOL "" FORCE)
+set(MLX_BUILD_SHARED_LIBS OFF CACHE BOOL "" FORCE)
+set(MLX_BUILD_GGUF OFF CACHE BOOL "" FORCE)
+set(MLX_BUILD_SAFETENSORS OFF CACHE BOOL "" FORCE)
+set(MLX_METAL_JIT OFF CACHE BOOL "" FORCE)
+
+# MLX uses FetchContent for json. When FetchContent_MakeAvailable(json) is called,
+# it will run add_subdirectory on the json source. ExecuTorch already adds json via
+# add_subdirectory(third-party/json) BEFORE this backend is processed.
+#
+# To prevent the conflict, we patch MLX's CMakeLists.txt to wrap the json fetch
+# in a target check. The patch file is in backends/apple/mlx/patches/
+
+# Ensure CMAKE_OSX_DEPLOYMENT_TARGET is set for MLX's version check.
+# MLX requires macOS >= 14.0. If not set, default to 14.0.
+if(NOT CMAKE_OSX_DEPLOYMENT_TARGET OR CMAKE_OSX_DEPLOYMENT_TARGET STREQUAL "")
+  set(CMAKE_OSX_DEPLOYMENT_TARGET "14.0" CACHE STRING "Minimum macOS version" FORCE)
+endif()
+
+FetchContent_Declare(
+  mlx
+  GIT_REPOSITORY https://github.com/ml-explore/mlx.git
+  GIT_TAG v0.30.3
+  PATCH_COMMAND git apply ${CMAKE_CURRENT_SOURCE_DIR}/patches/mlx_json.patch || true
+)
+
+message(STATUS "Fetching MLX...")
+FetchContent_MakeAvailable(mlx)
+
+# -----------------------------------------------------------------------------
+# MLX Backend library
+# -----------------------------------------------------------------------------
+
+set(_mlx_backend__srcs
+    ${CMAKE_CURRENT_SOURCE_DIR}/runtime/MLXLoader.cpp
+    ${CMAKE_CURRENT_SOURCE_DIR}/runtime/MLXBackend.cpp
+)
+
+add_library(mlxdelegate ${_mlx_backend__srcs})
+
+# Ensure schema is generated before compiling
+add_dependencies(mlxdelegate mlx_schema flatc)
+
+target_include_directories(
+  mlxdelegate
+  PRIVATE
+    ${CMAKE_CURRENT_SOURCE_DIR}/runtime
+    ${_mlx_schema__include_dir}
+    ${mlx_SOURCE_DIR}
+)
+
+# Link against MLX and executorch
+target_link_libraries(
+  mlxdelegate
+  PRIVATE
+    mlx_schema
+    executorch_core
+    mlx
+)
+
+executorch_target_link_options_shared_lib(mlxdelegate)
+target_compile_options(mlxdelegate PUBLIC ${_common_compile_options})
+
+install(
+  TARGETS mlxdelegate mlx_schema
+  EXPORT ExecuTorchTargets
+  DESTINATION ${CMAKE_INSTALL_LIBDIR}
+)
+
+# -----------------------------------------------------------------------------
+# Tests
+# -----------------------------------------------------------------------------
+
+add_subdirectory(test)
@@ -0,0 +1,17 @@
+#
+# 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.
+#
+
+"""MLX backend for ExecuTorch - executes models on Apple Silicon using MLX."""
+
+# Import ops module to register custom ops before anything else
+from executorch.backends.apple.mlx import ops as _ops  # noqa: F401
+
+from executorch.backends.apple.mlx.mlx_preprocess import MLXBackend
+from executorch.backends.apple.mlx.mlx_partitioner import MLXPartitioner
+
+__all__ = ["MLXBackend", "MLXPartitioner"]