diff --git a/libcxx/CMakeLists.txt b/libcxx/CMakeLists.txt
index 537ae80acc0b..2c708968dcea 100644
--- a/libcxx/CMakeLists.txt
+++ b/libcxx/CMakeLists.txt
@@ -19,16 +19,17 @@ set(CMAKE_MODULE_PATH
   ${CMAKE_MODULE_PATH}
   )
 
-# Find the LLVM sources and simulate LLVM CMake options.
-include(HandleOutOfTreeLLVM)
 
-if (LIBCXX_STANDALONE_BUILD)
+if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
   project(libcxx CXX C)
 
   set(PACKAGE_NAME libcxx)
   set(PACKAGE_VERSION 4.0.0svn)
   set(PACKAGE_STRING "${PACKAGE_NAME} ${PACKAGE_VERSION}")
   set(PACKAGE_BUGREPORT "llvm-bugs@lists.llvm.org")
+
+  # Find the LLVM sources and simulate LLVM CMake options.
+  include(HandleOutOfTreeLLVM)
 endif()
 
 if (LIBCXX_STANDALONE_BUILD AND NOT LLVM_FOUND)
@@ -59,7 +60,6 @@ option(LIBCXX_ENABLE_FILESYSTEM
         "Build filesystem as part of libc++experimental.a" ${LIBCXX_ENABLE_EXPERIMENTAL_LIBRARY})
 option(LIBCXX_INCLUDE_TESTS "Build the libc++ tests." ${LLVM_INCLUDE_TESTS})
 
-
 # Benchmark options -----------------------------------------------------------
 option(LIBCXX_INCLUDE_BENCHMARKS "Build the libc++ benchmarks and their dependancies" ON)
 set(LIBCXX_BENCHMARK_NATIVE_STDLIB "" CACHE STRING
@@ -535,11 +535,13 @@ include_directories(include)
 add_subdirectory(include)
 add_subdirectory(lib)
 
+
 if (LIBCXX_INCLUDE_BENCHMARKS)
   add_subdirectory(benchmarks)
 endif()
 if (LIBCXX_INCLUDE_TESTS)
   add_subdirectory(test)
+  add_subdirectory(lib/abi)
 endif()
 if (LIBCXX_INCLUDE_DOCS)
   add_subdirectory(docs)
diff --git a/libcxx/cmake/Modules/HandleOutOfTreeLLVM.cmake b/libcxx/cmake/Modules/HandleOutOfTreeLLVM.cmake
index 05b0244c3b54..599d8a1d4b20 100644
--- a/libcxx/cmake/Modules/HandleOutOfTreeLLVM.cmake
+++ b/libcxx/cmake/Modules/HandleOutOfTreeLLVM.cmake
@@ -11,6 +11,7 @@ macro(find_llvm_parts)
     set(LLVM_CMAKE_PATH "${LLVM_PATH}/cmake/modules")
   elseif(LLVM_CONFIG_PATH)
     message(STATUS "Found LLVM_CONFIG_PATH as ${LLVM_CONFIG_PATH}")
+    set(LIBCXX_USING_INSTALLED_LLVM 1)
     set(CONFIG_COMMAND ${LLVM_CONFIG_PATH}
       "--includedir"
       "--prefix"
@@ -56,21 +57,28 @@ macro(find_llvm_parts)
   set(LLVM_FOUND ON)
 endmacro(find_llvm_parts)
 
-# If this is a standalone build not running as an external project of LLVM
-# we need to later make some decisions differently.
-if(CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
-  # The intent is that this doesn't necessarily mean the LLVM is installed (it
-  # could be a build directory), but it means we need to treat the LLVM
-  # directory as read-only.
-  set(LIBCXX_USING_INSTALLED_LLVM 1)
-endif()
-
-if (LIBCXX_USING_INSTALLED_LLVM OR LIBCXX_STANDALONE_BUILD)
-  set(LIBCXX_STANDALONE_BUILD 1)
+macro(configure_out_of_tree_llvm)
   message(STATUS "Configuring for standalone build.")
+  set(LIBCXX_STANDALONE_BUILD 1)
 
   find_llvm_parts()
 
+  # Add LLVM Functions --------------------------------------------------------
+  if (LLVM_FOUND AND LIBCXX_USING_INSTALLED_LLVM)
+    include(LLVMConfig) # For TARGET_TRIPLE
+  else()
+    if (WIN32)
+      set(LLVM_ON_UNIX 0)
+      set(LLVM_ON_WIN32 1)
+    else()
+      set(LLVM_ON_UNIX 1)
+      set(LLVM_ON_WIN32 0)
+    endif()
+  endif()
+  if (LLVM_FOUND)
+    include(AddLLVM OPTIONAL)
+  endif()
+
   # LLVM Options --------------------------------------------------------------
   include(FindPythonInterp)
   if( NOT PYTHONINTERP_FOUND )
@@ -103,30 +111,11 @@ if (LIBCXX_USING_INSTALLED_LLVM OR LIBCXX_STANDALONE_BUILD)
     find_package(Sphinx REQUIRED)
   endif()
 
-  # FIXME - This is cribbed from HandleLLVMOptions.cmake.
-  if(WIN32)
+  if (LLVM_ON_UNIX AND NOT APPLE)
+    set(LLVM_HAVE_LINK_VERSION_SCRIPT 1)
+  else()
     set(LLVM_HAVE_LINK_VERSION_SCRIPT 0)
-    if(CYGWIN)
-      set(LLVM_ON_WIN32 0)
-      set(LLVM_ON_UNIX 1)
-    else(CYGWIN)
-      set(LLVM_ON_WIN32 1)
-      set(LLVM_ON_UNIX 0)
-    endif(CYGWIN)
-  else(WIN32)
-    if(UNIX)
-      set(LLVM_ON_WIN32 0)
-      set(LLVM_ON_UNIX 1)
-      if(APPLE)
-        set(LLVM_HAVE_LINK_VERSION_SCRIPT 0)
-      else(APPLE)
-        set(LLVM_HAVE_LINK_VERSION_SCRIPT 1)
-      endif(APPLE)
-    else(UNIX)
-      MESSAGE(SEND_ERROR "Unable to determine platform")
-    endif(UNIX)
-  endif(WIN32)
+  endif()
+endmacro(configure_out_of_tree_llvm)
 
-  # Add LLVM Functions --------------------------------------------------------
-  include(AddLLVM OPTIONAL)
-endif()
+configure_out_of_tree_llvm()
diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
index deed1a11052c..5969c6fa8ba5 100644
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -10,14 +10,18 @@ set(LIBCXX_HEADER_PATTERN
   ${LIBCXX_SUPPORT_HEADER_PATTERN}
   )
 
-if(NOT LIBCXX_USING_INSTALLED_LLVM)
-  file(COPY .
-    DESTINATION "${LLVM_BINARY_DIR}/include/c++/v1"
-    FILES_MATCHING
-    ${LIBCXX_HEADER_PATTERN}
-    )
+if (LIBCXX_STANDALONE_BUILD)
+  set(LIBCXX_BUILD_ROOT "${LIBCXX_BINARY_DIR}")
+else()
+  set(LIBCXX_BUILD_ROOT "${LLVM_BINARY_DIR}")
 endif()
 
+file(COPY .
+  DESTINATION "${LIBCXX_BUILD_ROOT}/include/c++/v1"
+  FILES_MATCHING
+  ${LIBCXX_HEADER_PATTERN}
+)
+
 if (LIBCXX_INSTALL_HEADERS)
   install(DIRECTORY .
     DESTINATION include/c++/v1
diff --git a/libcxx/lib/abi/CMakeLists.txt b/libcxx/lib/abi/CMakeLists.txt
new file mode 100644
index 000000000000..e67dcbe0fd59
--- /dev/null
+++ b/libcxx/lib/abi/CMakeLists.txt
@@ -0,0 +1,26 @@
+
+# Detect if we are building in the same configuration used to generate
+# the abilist files.
+if (DEFINED TARGET_TRIPLE
+    AND EXISTS "${CMAKE_CURRENT_LIST_DIR}/${TARGET_TRIPLE}.abilist"
+    AND TARGET cxx_shared
+    AND "${LIBCXX_CXX_ABI_LIBNAME}" STREQUAL "libcxxabi"
+    AND NOT LIBCXX_ABI_UNSTABLE
+    AND LIBCXX_ABI_VERSION EQUAL "1")
+    set(LIBCXX_HAS_ABILIST_CONFIGURATION 1 CACHE "")
+else()
+    if (NOT DEFINED LIBCXX_HAS_ABILIST_CONFIGURATION)
+        message(STATUS "libc++ configuration differs from the abilist configuration. check-cxx-abilist target is not supported")
+    endif()
+    set(LIBCXX_HAS_ABILIST_CONFIGURATION 0 CACHE "")
+endif()
+
+
+if (LIBCXX_HAS_ABILIST_CONFIGURATION)
+    set(ABILIST_FILE "${CMAKE_CURRENT_LIST_DIR}/${TARGET_TRIPLE}.abilist")
+    set(SYMDIFF_EXE "${LIBCXX_SOURCE_DIR}/utils/sym_check/sym_diff.py")
+    add_custom_target(check-cxx-abilist
+            ${SYMDIFF_EXE} ${ABILIST_FILE} $<TARGET_SONAME_FILE:cxx_shared>
+            DEPENDS cxx_shared
+            COMMENT "Testing ABI compatibility...")
+endif()
diff --git a/libcxx/lib/abi/x86_64-apple-darwin16.0.abilist b/libcxx/lib/abi/x86_64-apple-darwin16.0.0.abilist
similarity index 100%
rename from libcxx/lib/abi/x86_64-apple-darwin16.0.abilist
rename to libcxx/lib/abi/x86_64-apple-darwin16.0.0.abilist
diff --git a/libcxx/lib/abi/x86_64-linux-gnu.abilist b/libcxx/lib/abi/x86_64-unknown-linux-gnu.abilist
similarity index 100%
rename from libcxx/lib/abi/x86_64-linux-gnu.abilist
rename to libcxx/lib/abi/x86_64-unknown-linux-gnu.abilist