diff --git a/libcxx/CMakeLists.txt b/libcxx/CMakeLists.txt
--- a/libcxx/CMakeLists.txt
+++ b/libcxx/CMakeLists.txt
@@ -272,9 +272,6 @@
 
 # Target options --------------------------------------------------------------
 option(LIBCXX_BUILD_32_BITS "Build 32 bit libc++." ${LLVM_BUILD_32_BITS})
-set(LIBCXX_TARGET_TRIPLE "${LLVM_DEFAULT_TARGET_TRIPLE}" CACHE STRING "Use alternate target triple.")
-set(LIBCXX_SYSROOT "" CACHE STRING "Use alternate sysroot.")
-set(LIBCXX_GCC_TOOLCHAIN "" CACHE STRING "Use alternate GCC toolchain.")
 
 # Feature options -------------------------------------------------------------
 option(LIBCXX_ENABLE_EXCEPTIONS "Use exceptions." ON)
@@ -487,22 +484,6 @@
 # 'LIBCXX_COMPILE_FLAGS' and 'LIBCXX_LINK_FLAGS'
 add_target_flags_if(LIBCXX_BUILD_32_BITS "-m32")
 
-if(LIBCXX_TARGET_TRIPLE)
-  add_target_flags_if_supported("--target=${LIBCXX_TARGET_TRIPLE}")
-elseif(CMAKE_CXX_COMPILER_TARGET)
-  set(LIBCXX_TARGET_TRIPLE "${CMAKE_CXX_COMPILER_TARGET}")
-endif()
-if(LIBCXX_SYSROOT)
-  add_target_flags_if_supported("--sysroot=${LIBCXX_SYSROOT}")
-elseif(CMAKE_SYSROOT)
-  set(LIBCXX_SYSROOT "${CMAKE_SYSROOT}")
-endif()
-if(LIBCXX_GCC_TOOLCHAIN)
-  add_target_flags_if_supported("--gcc-toolchain=${LIBCXX_GCC_TOOLCHAIN}")
-elseif(CMAKE_CXX_COMPILER_EXTERNAL_TOOLCHAIN)
-  set(LIBCXX_GCC_TOOLCHAIN "${CMAKE_CXX_COMPILER_EXTERNAL_TOOLCHAIN}")
-endif()
-
 # Configure compiler.
 include(config-ix)
 
diff --git a/libcxx/cmake/caches/AArch64.cmake b/libcxx/cmake/caches/AArch64.cmake
--- a/libcxx/cmake/caches/AArch64.cmake
+++ b/libcxx/cmake/caches/AArch64.cmake
@@ -1,2 +1,2 @@
 set(LIBCXXABI_USE_LLVM_UNWINDER ON CACHE BOOL "")
-set(LIBCXX_TARGET_TRIPLE "aarch64-linux-gnu" CACHE STRING "")
+set(CMAKE_CXX_COMPILER_TARGET "aarch64-linux-gnu" CACHE STRING "")
diff --git a/libcxx/cmake/caches/Armv7Arm.cmake b/libcxx/cmake/caches/Armv7Arm.cmake
--- a/libcxx/cmake/caches/Armv7Arm.cmake
+++ b/libcxx/cmake/caches/Armv7Arm.cmake
@@ -1,4 +1,4 @@
 set(LIBCXXABI_USE_LLVM_UNWINDER ON CACHE BOOL "")
-set(LIBCXX_TARGET_TRIPLE "armv7-linux-gnueabihf" CACHE STRING "")
+set(CMAKE_CXX_COMPILER_TARGET "armv7-linux-gnueabihf" CACHE STRING "")
 set(CMAKE_CXX_FLAGS "-marm" CACHE STRING "")
 set(CMAKE_C_FLAGS "-marm" CACHE STRING "")
diff --git a/libcxx/cmake/caches/Armv7Thumb-noexceptions.cmake b/libcxx/cmake/caches/Armv7Thumb-noexceptions.cmake
--- a/libcxx/cmake/caches/Armv7Thumb-noexceptions.cmake
+++ b/libcxx/cmake/caches/Armv7Thumb-noexceptions.cmake
@@ -1,5 +1,5 @@
 set(LIBCXXABI_USE_LLVM_UNWINDER ON CACHE BOOL "")
-set(LIBCXX_TARGET_TRIPLE "armv7-linux-gnueabihf" CACHE STRING "")
+set(CMAKE_CXX_COMPILER_TARGET "armv7-linux-gnueabihf" CACHE STRING "")
 set(CMAKE_CXX_FLAGS "-mthumb" CACHE STRING "")
 set(CMAKE_C_FLAGS "-mthumb" CACHE STRING "")
 set(LIBCXX_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
diff --git a/libcxx/cmake/caches/Armv8Arm.cmake b/libcxx/cmake/caches/Armv8Arm.cmake
--- a/libcxx/cmake/caches/Armv8Arm.cmake
+++ b/libcxx/cmake/caches/Armv8Arm.cmake
@@ -1,4 +1,4 @@
 set(LIBCXXABI_USE_LLVM_UNWINDER ON CACHE BOOL "")
-set(LIBCXX_TARGET_TRIPLE "armv8-linux-gnueabihf" CACHE STRING "")
+set(CMAKE_CXX_COMPILER_TARGET "armv8-linux-gnueabihf" CACHE STRING "")
 set(CMAKE_CXX_FLAGS "-marm" CACHE STRING "")
 set(CMAKE_C_FLAGS "-marm" CACHE STRING "")
diff --git a/libcxx/cmake/caches/Armv8Thumb-noexceptions.cmake b/libcxx/cmake/caches/Armv8Thumb-noexceptions.cmake
--- a/libcxx/cmake/caches/Armv8Thumb-noexceptions.cmake
+++ b/libcxx/cmake/caches/Armv8Thumb-noexceptions.cmake
@@ -1,5 +1,5 @@
 set(LIBCXXABI_USE_LLVM_UNWINDER ON CACHE BOOL "")
-set(LIBCXX_TARGET_TRIPLE "armv8-linux-gnueabihf" CACHE STRING "")
+set(CMAKE_CXX_COMPILER_TARGET "armv8-linux-gnueabihf" CACHE STRING "")
 set(CMAKE_CXX_FLAGS "-mthumb" CACHE STRING "")
 set(CMAKE_C_FLAGS "-mthumb" CACHE STRING "")
 set(LIBCXX_ENABLE_EXCEPTIONS OFF CACHE BOOL "")
diff --git a/libcxx/docs/BuildingLibcxx.rst b/libcxx/docs/BuildingLibcxx.rst
--- a/libcxx/docs/BuildingLibcxx.rst
+++ b/libcxx/docs/BuildingLibcxx.rst
@@ -136,7 +136,7 @@
 
 If you are running in an MSYS2 shell and you have installed the
 MSYS2-provided clang package (which defaults to a non-MSVC target), you
-should add e.g. ``-DLIBCXX_TARGET_TRIPLE=x86_64-windows-msvc`` (replacing
+should add e.g. ``-DCMAKE_CXX_COMPILER_TARGET=x86_64-windows-msvc`` (replacing
 ``x86_64`` with the architecture you're targeting) to the ``cmake`` command
 line above. This will instruct ``check-cxx`` to use the right target triple
 when invoking ``clang++``.
diff --git a/libcxx/lib/abi/CMakeLists.txt b/libcxx/lib/abi/CMakeLists.txt
--- a/libcxx/lib/abi/CMakeLists.txt
+++ b/libcxx/lib/abi/CMakeLists.txt
@@ -41,7 +41,7 @@
 endfunction()
 
 cxx_abi_list_identifier(abi_list_identifier
-  "${LIBCXX_TARGET_TRIPLE}"
+  "${CMAKE_CXX_COMPILER_TARGET}"
   "${LIBCXX_CXX_ABI_LIBNAME}"
   "${LIBCXX_ABI_VERSION}"
   "${LIBCXX_ABI_UNSTABLE}"
diff --git a/libcxx/test/CMakeLists.txt b/libcxx/test/CMakeLists.txt
--- a/libcxx/test/CMakeLists.txt
+++ b/libcxx/test/CMakeLists.txt
@@ -105,8 +105,8 @@
   serialize_lit_param(enable_debug_tests False)
 endif()
 
-if (LIBCXX_TARGET_TRIPLE)
-  serialize_lit_param(target_triple "\"${LIBCXX_TARGET_TRIPLE}\"")
+if (CMAKE_CXX_COMPILER_TARGET)
+  serialize_lit_param(target_triple "\"${CMAKE_CXX_COMPILER_TARGET}\"")
 endif()
 
 if (LLVM_USE_SANITIZER)
diff --git a/libcxx/test/configs/legacy.cfg.in b/libcxx/test/configs/legacy.cfg.in
--- a/libcxx/test/configs/legacy.cfg.in
+++ b/libcxx/test/configs/legacy.cfg.in
@@ -17,8 +17,8 @@
 config.cxx_abi                  = "@LIBCXX_CXX_ABI_LIBNAME@"
 config.configuration_variant    = "@LIBCXX_LIT_VARIANT@"
 config.host_triple              = "@LLVM_HOST_TRIPLE@"
-config.sysroot                  = "@LIBCXX_SYSROOT@"
-config.gcc_toolchain            = "@LIBCXX_GCC_TOOLCHAIN@"
+config.sysroot                  = "@CMAKE_SYSROOT@"
+config.gcc_toolchain            = "@CMAKE_CXX_COMPILER_EXTERNAL_TOOLCHAIN@"
 config.generate_coverage        = @LIBCXX_GENERATE_COVERAGE@
 config.target_info              = "@LIBCXX_TARGET_INFO@"
 config.test_linker_flags        = "@LIBCXX_TEST_LINKER_FLAGS@"
diff --git a/libcxxabi/CMakeLists.txt b/libcxxabi/CMakeLists.txt
--- a/libcxxabi/CMakeLists.txt
+++ b/libcxxabi/CMakeLists.txt
@@ -113,9 +113,6 @@
 set(LIBCXXABI_LIBDIR_SUFFIX "${LLVM_LIBDIR_SUFFIX}" CACHE STRING
     "Define suffix of library directory name (32/64)")
 option(LIBCXXABI_INSTALL_LIBRARY "Install the libc++abi library." ON)
-set(LIBCXXABI_TARGET_TRIPLE "${LLVM_DEFAULT_TARGET_TRIPLE}" CACHE STRING "Target triple for cross compiling.")
-set(LIBCXXABI_GCC_TOOLCHAIN "" CACHE PATH "GCC toolchain for cross compiling.")
-set(LIBCXXABI_SYSROOT "" CACHE PATH "Sysroot for cross compiling.")
 set(LIBCXXABI_LIBCXX_LIBRARY_PATH "" CACHE PATH "The path to libc++ library.")
 set(LIBCXXABI_LIBRARY_VERSION "1.0" CACHE STRING
 "Version of libc++abi. This will be reflected in the name of the shared \
@@ -269,22 +266,6 @@
 # Configure target flags
 add_target_flags_if(LIBCXXABI_BUILD_32_BITS "-m32")
 
-if(LIBCXXABI_TARGET_TRIPLE)
-  add_target_flags_if_supported("--target=${LIBCXXABI_TARGET_TRIPLE}")
-elseif(CMAKE_CXX_COMPILER_TARGET)
-  set(LIBCXXABI_TARGET_TRIPLE "${CMAKE_CXX_COMPILER_TARGET}")
-endif()
-if(LIBCXX_GCC_TOOLCHAIN)
-  add_target_flags_if_supported("--gcc-toolchain=${LIBCXXABI_GCC_TOOLCHAIN}")
-elseif(CMAKE_CXX_COMPILER_EXTERNAL_TOOLCHAIN)
-  set(LIBCXXABI_GCC_TOOLCHAIN "${CMAKE_CXX_COMPILER_EXTERNAL_TOOLCHAIN}")
-endif()
-if(LIBCXXABI_SYSROOT)
-  add_target_flags_if_supported("--sysroot=${LIBCXXABI_SYSROOT}")
-elseif(CMAKE_SYSROOT)
-  set(LIBCXXABI_SYSROOT "${CMAKE_SYSROOT}")
-endif()
-
 # Configure compiler. Must happen after setting the target flags.
 include(config-ix)
 
diff --git a/libcxxabi/test/CMakeLists.txt b/libcxxabi/test/CMakeLists.txt
--- a/libcxxabi/test/CMakeLists.txt
+++ b/libcxxabi/test/CMakeLists.txt
@@ -86,8 +86,8 @@
   serialize_lit_param(use_sanitizer "\"${LLVM_USE_SANITIZER}\"")
 endif()
 
-if (LIBCXXABI_TARGET_TRIPLE)
-  serialize_lit_param(target_triple "\"${LIBCXXABI_TARGET_TRIPLE}\"")
+if (CMAKE_CXX_COMPILER_TARGET)
+  serialize_lit_param(target_triple "\"${CMAKE_CXX_COMPILER_TARGET}\"")
 endif()
 
 if (LIBCXXABI_BUILD_32_BITS)
diff --git a/libcxxabi/test/lit.site.cfg.in b/libcxxabi/test/lit.site.cfg.in
--- a/libcxxabi/test/lit.site.cfg.in
+++ b/libcxxabi/test/lit.site.cfg.in
@@ -24,8 +24,8 @@
 config.libcxxabi_shared         = @LIBCXXABI_LINK_TESTS_WITH_SHARED_LIBCXXABI@
 config.enable_shared            = @LIBCXXABI_LINK_TESTS_WITH_SHARED_LIBCXX@
 config.host_triple              = "@LLVM_HOST_TRIPLE@"
-config.sysroot                  = "@LIBCXXABI_SYSROOT@"
-config.gcc_toolchain            = "@LIBCXXABI_GCC_TOOLCHAIN@"
+config.sysroot                  = "@CMAKE_SYSROOT@"
+config.gcc_toolchain            = "@CMAKE_CXX_COMPILER_EXTERNAL_TOOLCHAIN@"
 config.cxx_ext_threads          = @LIBCXXABI_BUILD_EXTERNAL_THREAD_LIBRARY@
 
 config.pstl_src_root            = "@ParallelSTL_SOURCE_DIR@" if @LIBCXX_ENABLE_PARALLEL_ALGORITHMS@ else None
diff --git a/libunwind/CMakeLists.txt b/libunwind/CMakeLists.txt
--- a/libunwind/CMakeLists.txt
+++ b/libunwind/CMakeLists.txt
@@ -80,9 +80,6 @@
 cmake_dependent_option(LIBUNWIND_INSTALL_SHARED_LIBRARY
   "Install the shared libunwind library." ON
   "LIBUNWIND_ENABLE_SHARED;LIBUNWIND_INSTALL_LIBRARY" OFF)
-set(LIBUNWIND_TARGET_TRIPLE "${LLVM_DEFAULT_TARGET_TRIPLE}" CACHE STRING "Target triple for cross compiling.")
-set(LIBUNWIND_GCC_TOOLCHAIN "" CACHE PATH "GCC toolchain for cross compiling.")
-set(LIBUNWIND_SYSROOT "" CACHE PATH "Sysroot for cross compiling.")
 set(LIBUNWIND_TEST_LINKER_FLAGS "" CACHE STRING
     "Additional linker flags for test programs.")
 set(LIBUNWIND_TEST_COMPILER_FLAGS "" CACHE STRING
@@ -174,22 +171,6 @@
 # Get required flags.
 add_target_flags_if(LIBUNWIND_BUILD_32_BITS "-m32")
 
-if(LIBUNWIND_TARGET_TRIPLE)
-  add_target_flags_if_supported("--target=${LIBUNWIND_TARGET_TRIPLE}")
-elseif(CMAKE_CXX_COMPILER_TARGET)
-  set(LIBUNWIND_TARGET_TRIPLE "${CMAKE_CXX_COMPILER_TARGET}")
-endif()
-if(LIBUNWIND_GCC_TOOLCHAIN)
-  add_target_flags_if_supported("--gcc-toolchain=${LIBUNWIND_GCC_TOOLCHAIN}")
-elseif(CMAKE_CXX_COMPILER_EXTERNAL_TOOLCHAIN)
-  set(LIBUNWIND_GCC_TOOLCHAIN "${CMAKE_CXX_COMPILER_EXTERNAL_TOOLCHAIN}")
-endif()
-if(LIBUNWIND_SYSROOT)
-  add_target_flags_if_supported("--sysroot=${LIBUNWIND_SYSROOT}")
-elseif(CMAKE_SYSROOT)
-  set(LIBUNWIND_SYSROOT "${CMAKE_SYSROOT}")
-endif()
-
 # Configure compiler.
 include(config-ix)
 
diff --git a/libunwind/docs/BuildingLibunwind.rst b/libunwind/docs/BuildingLibunwind.rst
--- a/libunwind/docs/BuildingLibunwind.rst
+++ b/libunwind/docs/BuildingLibunwind.rst
@@ -148,18 +148,6 @@
 
   Build libunwind with threading support.
 
-.. option:: LIBUNWIND_TARGET_TRIPLE:STRING
-
-  Target triple for cross compiling
-
-.. option:: LIBUNWIND_GCC_TOOLCHAIN:PATH
-
-  GCC toolchain for cross compiling
-
-.. option:: LIBUNWIND_SYSROOT
-
-  Sysroot for cross compiling
-
 .. option:: LIBUNWIND_INSTALL_LIBRARY_DIR:PATH
 
   **Default**: ``lib${LIBUNWIND_LIBDIR_SUFFIX}``
diff --git a/libunwind/test/CMakeLists.txt b/libunwind/test/CMakeLists.txt
--- a/libunwind/test/CMakeLists.txt
+++ b/libunwind/test/CMakeLists.txt
@@ -37,8 +37,8 @@
   serialize_lit_param(use_sanitizer "\"${LLVM_USE_SANITIZER}\"")
 endif()
 
-if (LIBUNWIND_TARGET_TRIPLE)
-  serialize_lit_param(target_triple "\"${LIBUNWIND_TARGET_TRIPLE}\"")
+if (CMAKE_CXX_COMPILER_TARGET)
+  serialize_lit_param(target_triple "\"${CMAKE_CXX_COMPILER_TARGET}\"")
 endif()
 
 if (LIBUNWIND_BUILD_32_BITS)
diff --git a/libunwind/test/lit.site.cfg.in b/libunwind/test/lit.site.cfg.in
--- a/libunwind/test/lit.site.cfg.in
+++ b/libunwind/test/lit.site.cfg.in
@@ -25,8 +25,8 @@
 config.enable_shared            = @LIBCXX_ENABLE_SHARED@
 config.arm_ehabi                = @LIBUNWIND_USES_ARM_EHABI@
 config.host_triple              = "@LLVM_HOST_TRIPLE@"
-config.sysroot                  = "@LIBUNWIND_SYSROOT@"
-config.gcc_toolchain            = "@LIBUNWIND_GCC_TOOLCHAIN@"
+config.sysroot                  = "@CMAKE_SYSROOT@"
+config.gcc_toolchain            = "@CMAKE_CXX_COMPILER_EXTERNAL_TOOLCHAIN@"
 config.cxx_ext_threads          = @LIBUNWIND_BUILD_EXTERNAL_THREAD_LIBRARY@
 config.x86_cet                  = @LIBUNWIND_ENABLE_CET@