diff --git a/extension/data_loader/CMakeLists.txt b/extension/data_loader/CMakeLists.txt
index 104cd23c977..a5e7a0c4a81 100644
--- a/extension/data_loader/CMakeLists.txt
+++ b/extension/data_loader/CMakeLists.txt
@@ -24,6 +24,11 @@ if(NOT ET_HAVE_SYS_MMAN_H AND NOT WIN32)
        "extension/data_loader/mmap_data_loader.cpp"
   )
 endif()
+if(WIN32)
+  list(APPEND _extension_data_loader__srcs
+       "extension/data_loader/mman_windows.cpp"
+  )
+endif()
 list(TRANSFORM _extension_data_loader__srcs PREPEND "${EXECUTORCH_ROOT}/")
 add_library(extension_data_loader ${_extension_data_loader__srcs})
 target_link_libraries(extension_data_loader executorch_core)
diff --git a/tools/cmake/preset/pybind.cmake b/tools/cmake/preset/pybind.cmake
index e13fe026ef2..2a69a33cee4 100644
--- a/tools/cmake/preset/pybind.cmake
+++ b/tools/cmake/preset/pybind.cmake
@@ -21,16 +21,28 @@ set_overridable_option(EXECUTORCH_BUILD_EXTENSION_FLAT_TENSOR ON)
 set_overridable_option(EXECUTORCH_BUILD_EXTENSION_DATA_LOADER ON)
 set_overridable_option(EXECUTORCH_BUILD_KERNELS_OPTIMIZED ON)
 set_overridable_option(EXECUTORCH_BUILD_EXTENSION_MODULE ON)
-set_overridable_option(EXECUTORCH_BUILD_EXTENSION_TRAINING ON)
 
 if(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
   set_overridable_option(EXECUTORCH_BUILD_COREML ON)
+  set_overridable_option(EXECUTORCH_BUILD_EXTENSION_TRAINING ON)
 elseif(CMAKE_SYSTEM_NAME STREQUAL "Linux")
   set_overridable_option(EXECUTORCH_BUILD_COREML ON)
+  set_overridable_option(EXECUTORCH_BUILD_EXTENSION_TRAINING ON)
 elseif(CMAKE_SYSTEM_NAME STREQUAL "Windows" OR CMAKE_SYSTEM_NAME STREQUAL
                                                "WIN32"
 )
-  # Windows or other OS-specific code here
+  if(NOT CMAKE_GENERATOR_TOOLSET MATCHES "ClangCL")
+    message(
+      FATAL_ERROR
+        "ExecuTorch requires the ClangCL toolset on Windows. Please configure with -T ClangCL."
+    )
+  endif()
+
+  # These XNNPACK options don't currently build on Windows with Clang.
+  set_overridable_option(XNNPACK_ENABLE_AVX256SKX OFF)
+  set_overridable_option(XNNPACK_ENABLE_AVX256VNNI OFF)
+  set_overridable_option(XNNPACK_ENABLE_AVX256VNNIGFNI OFF)
+  set_overridable_option(XNNPACK_ENABLE_AVX512BF16 OFF)
 else()
   message(
     FATAL_ERROR "Unsupported CMAKE_SYSTEM_NAME for pybind: ${CMAKE_SYSTEM_NAME}"