diff --git a/cmake/CMakeLists.txt b/cmake/CMakeLists.txt
index a027c69e0..eb7608518 100644
--- a/cmake/CMakeLists.txt
+++ b/cmake/CMakeLists.txt
@@ -753,7 +753,8 @@ get_filename_component(ORTTRAINING_ROOT "${ORTTRAINING_ROOT}" ABSOLUTE)
 get_filename_component(REPO_ROOT "${REPO_ROOT}" ABSOLUTE)
 set(ONNXRUNTIME_INCLUDE_DIR ${REPO_ROOT}/include/onnxruntime)
 
-add_subdirectory(external/date EXCLUDE_FROM_ALL)
+find_package(date REQUIRED)
+add_library(date_interface ALIAS date::date)
 
 set(SAFEINT_INCLUDE_DIR ${REPO_ROOT}/cmake/external/SafeInt)
 add_library(safeint_interface INTERFACE)
@@ -764,14 +765,17 @@ if(onnxruntime_DISABLE_EXCEPTIONS)
   add_compile_definitions(optional_CONFIG_NO_EXCEPTIONS=1)
 endif()
 
-add_subdirectory(external/mp11 EXCLUDE_FROM_ALL)
+add_library(boost_mp11 INTERFACE)
+add_library(Boost::mp11 ALIAS boost_mp11)
 
 set(JSON_BuildTests OFF CACHE INTERNAL "")
 set(JSON_Install OFF CACHE INTERNAL "")
-add_subdirectory(external/json EXCLUDE_FROM_ALL)
+find_package(nlohmann_json REQUIRED)
 
 if(onnxruntime_PREFER_SYSTEM_LIB)
-  find_package(re2)
+  find_package(PkgConfig)
+  pkg_check_modules(RE2 IMPORTED_TARGET re2)
+  add_library(re2::re2 ALIAS PkgConfig::RE2)
 endif()
 if(NOT TARGET re2::re2)
   add_subdirectory(external/re2 EXCLUDE_FROM_ALL)
@@ -1261,7 +1265,8 @@ set(FLATBUFFERS_INSTALL OFF CACHE BOOL "FLATBUFFERS_INSTALL" FORCE)
 set(FLATBUFFERS_BUILD_FLATHASH OFF CACHE BOOL "FLATBUFFERS_BUILD_FLATHASH" FORCE)
 set(FLATBUFFERS_BUILD_FLATLIB ON CACHE BOOL "FLATBUFFERS_BUILD_FLATLIB" FORCE)
 set_msvc_c_cpp_compiler_warning_level(4)
-add_subdirectory(external/flatbuffers EXCLUDE_FROM_ALL)
+find_package(Flatbuffers REQUIRED)
+add_library(flatbuffers ALIAS flatbuffers::flatbuffers_shared)
 set_msvc_c_cpp_compiler_warning_level(3)
 list(APPEND onnxruntime_EXTERNAL_DEPENDENCIES flatbuffers)
 list(APPEND onnxruntime_EXTERNAL_LIBRARIES flatbuffers)