https://github.com/BYVoid/OpenCC/issues/547

--- /CMakeLists.txt
+++ /CMakeLists.txt
@@ -28,8 +28,14 @@
 option(ENABLE_GTEST "Build all tests." OFF)
 option(ENABLE_BENCHMARK "Build benchmark tests." OFF)
 option(ENABLE_DARTS "Build DartsDict (ocd format)." ON)
-option(BUILD_BUNDLED_LIBMARISA "" ON)
 option(BUILD_PYTHON "Build python library" OFF)
+option(USE_SYSTEM_DARTS "Use system version of Darts" OFF)
+option(USE_SYSTEM_GOOGLE_BENCHMARK "Use system version of Google Benchmark" OFF)
+option(USE_SYSTEM_GTEST "Use system version of GoogleTest" OFF)
+option(USE_SYSTEM_MARISA "Use system version of Marisa" OFF)
+option(USE_SYSTEM_PYBIND11 "Use system version of pybind11" OFF)
+option(USE_SYSTEM_RAPIDJSON "Use system version of RapidJSON" OFF)
+option(USE_SYSTEM_TCLAP "Use system version of TCLAP" OFF)
 
 ######## Package information
 set (PACKAGE_URL https://github.com/BYVoid/Opencc)
@@ -173,7 +179,7 @@
 
 ######## Dependencies
 
-if(BUILD_BUNDLED_LIBMARISA)
+if(NOT USE_SYSTEM_MARISA)
   message(STATUS "Use bundled marisa library.")
   add_subdirectory(deps/marisa-0.2.5)
 else()
@@ -195,20 +201,30 @@
 ######## Testing
 
 if (ENABLE_GTEST)
-  add_subdirectory(deps/gtest-1.11.0)
+  if(NOT USE_SYSTEM_GTEST)
+    add_subdirectory(deps/gtest-1.11.0)
+  endif()
   enable_testing()
 endif()
 
 if (ENABLE_BENCHMARK)
   set(BENCHMARK_ENABLE_TESTING OFF)
-  add_subdirectory(deps/google-benchmark)
+  if(NOT USE_SYSTEM_GOOGLE_BENCHMARK)
+    add_subdirectory(deps/google-benchmark)
+  endif()
   enable_testing()
 endif()
 
 ######## Python
 
 if (BUILD_PYTHON)
-  add_subdirectory(deps/pybind11-2.5.0)
+  if(USE_SYSTEM_PYBIND11)
+    include(pybind11Config)
+    include(pybind11Common)
+    include(pybind11Tools)
+  else()
+    add_subdirectory(deps/pybind11-2.5.0)
+  endif()
   pybind11_add_module(opencc_clib src/py_opencc.cpp)
   target_link_libraries(opencc_clib PRIVATE libopencc)
 endif()
--- /src/CMakeLists.txt
+++ /src/CMakeLists.txt
@@ -1,7 +1,13 @@
 include (GenerateExportHeader)
-include_directories(../deps/marisa-0.2.5/include)
-include_directories(../deps/rapidjson-1.1.0)
-include_directories(../deps/tclap-1.2.2)
+if(NOT USE_SYSTEM_MARISA)
+  include_directories(../deps/marisa-0.2.5/include)
+endif()
+if(NOT USE_SYSTEM_RAPIDJSON)
+  include_directories(../deps/rapidjson-1.1.0)
+endif()
+if(NOT USE_SYSTEM_TCLAP)
+  include_directories(../deps/tclap-1.2.2)
+endif()
 
 # Library
 
@@ -72,7 +78,9 @@
 )
 
 if (ENABLE_DARTS)
-  include_directories(../deps/darts-clone)
+  if(NOT USE_SYSTEM_DARTS)
+    include_directories(../deps/darts-clone)
+  endif()
   set(
     LIBOPENCC_HEADERS
     ${LIBOPENCC_HEADERS}
--- /test/CMakeLists.txt
+++ /test/CMakeLists.txt
@@ -1,4 +1,3 @@
-include_directories(../deps/libdarts/src)
 include_directories(../src)
 
 set(CONFIG_TEST
@@ -27,7 +26,9 @@
     )
   endif()
 
-  include_directories(../deps/gtest-1.7.0/include)
+  if(NOT USE_SYSTEM_GTEST)
+    include_directories(../deps/gtest-1.7.0/include)
+  endif()
   set(UNITTESTS
     CommandLineConvertTest
   )