Index: llvm/cmake/modules/HandleLLVMOptions.cmake
===================================================================
--- llvm/cmake/modules/HandleLLVMOptions.cmake
+++ llvm/cmake/modules/HandleLLVMOptions.cmake
@@ -806,6 +806,17 @@
     # Always ask the linker to produce symbols with asan.
     append("/Z7" CMAKE_C_FLAGS CMAKE_CXX_FLAGS)
     append("-debug" CMAKE_EXE_LINKER_FLAGS CMAKE_MODULE_LINKER_FLAGS CMAKE_SHARED_LINKER_FLAGS)
+  elseif (MSVC)
+    check_cxx_source_compiles(
+      "#include <sanitizer/asan_interface.h> int main() { return 0; }"
+      msvc_sanitizer_include_enabled)
+    if(NOT msvc_sanitizer_include_enabled)
+      file(TO_CMAKE_PATH "$ENV{VCToolsInstallDir}/crt/src" MSVC_CRT_SRC_DIR)
+      if(NOT EXISTS "${MSVC_CRT_SRC_DIR}/sanitizer")
+        message(WARNING "Sanitizer include directory not found in ${MSVC_CRT_SRC_DIR}")
+      endif()
+      include_directories(SYSTEM ${MSVC_CRT_SRC_DIR})
+    endif()
   endif()
 endmacro()