Index: cmake/caches/Fuchsia-stage2.cmake
===================================================================
--- /dev/null
+++ cmake/caches/Fuchsia-stage2.cmake
@@ -0,0 +1,64 @@
+# This file sets up a CMakeCache for the second stage of a Fuchsia toolchain
+# build.
+
+set(LLVM_TARGETS_TO_BUILD X86;AArch64 CACHE STRING "")
+
+set(PACKAGE_VENDOR Fuchsia CACHE STRING "")
+
+set(LLVM_INCLUDE_EXAMPLES OFF CACHE BOOL "")
+set(LLVM_INCLUDE_DOCS OFF CACHE BOOL "")
+set(LLVM_TOOL_CLANG_TOOLS_EXTRA_BUILD OFF CACHE BOOL "")
+set(LLVM_ENABLE_ZLIB ON CACHE BOOL "")
+set(LLVM_ENABLE_BACKTRACES OFF CACHE BOOL "")
+set(LLVM_EXTERNALIZE_DEBUGINFO ON CACHE BOOL "")
+set(CLANG_PLUGIN_SUPPORT OFF CACHE BOOL "")
+
+set(LLVM_ENABLE_LTO ON CACHE BOOL "")
+if(NOT APPLE)
+  set(LLVM_ENABLE_LLD ON CACHE BOOL "")
+  set(CLANG_DEFAULT_LINKER lld CACHE STRING "")
+endif()
+
+#set(CLANG_DEFAULT_CXX_STDLIB libc++ CACHE STRING "")
+
+#set(CMAKE_BUILD_TYPE Release CACHE STRING "")
+set(CMAKE_BUILD_TYPE RelWithDebInfo CACHE STRING "")
+set(CMAKE_C_FLAGS_RELWITHDEBINFO "-O2 -gline-tables-only -DNDEBUG" CACHE STRING "")
+set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "-O2 -gline-tables-only -DNDEBUG" CACHE STRING "")
+
+set(LLVM_BUILTIN_TARGETS "x86_64-fuchsia-none;aarch64-fuchsia-none" CACHE STRING "")
+set(BUILTINS_x86_64-fuchsia-none_CMAKE_SYSROOT ${FUCHSIA_SYSROOT} CACHE STRING "")
+set(BUILTINS_x86_64-fuchsia-none_CMAKE_SYSTEM_NAME Fuchsia CACHE STRING "")
+set(BUILTINS_aarch64-fuchsia-none_CMAKE_SYSROOT ${FUCHSIA_SYSROOT} CACHE STRING "")
+set(BUILTINS_aarch64-fuchsia-none_CMAKE_SYSTEM_NAME Fuchsia CACHE STRING "")
+
+# Setup toolchain.
+set(LLVM_INSTALL_TOOLCHAIN_ONLY ON CACHE BOOL "")
+set(LLVM_TOOLCHAIN_TOOLS
+  llvm-ar
+  llvm-cov
+  llvm-cxxfilt
+  llvm-dwarfdump
+  llvm-dsymutil
+  llvm-lib
+  llvm-nm
+  llvm-objdump
+  llvm-profdata
+  llvm-ranlib
+  llvm-readobj
+  llvm-size
+  llvm-symbolizer
+  CACHE STRING "")
+
+set(LLVM_DISTRIBUTION_COMPONENTS
+  clang
+  lld
+  lldb
+  LTO
+  clang-format
+  clang-headers
+  builtins-x86_64-fuchsia-none
+  builtins-aarch64-fuchsia-none
+  runtimes
+  ${LLVM_TOOLCHAIN_TOOLS}
+  CACHE STRING "")
Index: cmake/caches/Fuchsia.cmake
===================================================================
--- /dev/null
+++ cmake/caches/Fuchsia.cmake
@@ -0,0 +1,44 @@
+# This file sets up a CMakeCache for a Fuchsia toolchain build.
+
+set(LLVM_TARGETS_TO_BUILD Native CACHE STRING "")
+
+set(PACKAGE_VENDOR Fuchsia CACHE STRING "")
+
+set(LLVM_INCLUDE_EXAMPLES OFF CACHE BOOL "")
+set(LLVM_INCLUDE_TESTS OFF CACHE BOOL "")
+set(LLVM_INCLUDE_DOCS OFF CACHE BOOL "")
+set(CLANG_INCLUDE_TESTS OFF CACHE BOOL "")
+set(LLVM_ENABLE_ZLIB OFF CACHE BOOL "")
+set(LLVM_ENABLE_BACKTRACES OFF CACHE BOOL "")
+set(CLANG_PLUGIN_SUPPORT OFF CACHE BOOL "")
+
+set(CMAKE_BUILD_TYPE Release CACHE STRING "")
+
+set(BOOTSTRAP_LLVM_ENABLE_LTO ON CACHE BOOL "")
+if(NOT APPLE)
+  set(BOOTSTRAP_LLVM_ENABLE_LLD ON CACHE BOOL "")
+endif()
+
+set(CLANG_BOOTSTRAP_TARGETS
+  check-all
+  check-llvm
+  check-clang
+  llvm-config
+  test-suite
+  test-depends
+  llvm-test-depends
+  clang-test-depends
+  distribution
+  install-distribution
+  clang CACHE STRING "")
+
+if(FUCHSIA_SYSROOT)
+  set(EXTRA_ARGS -DFUCHSIA_SYSROOT=${FUCHSIA_SYSROOT})
+endif()
+
+# Setup the bootstrap build.
+set(CLANG_ENABLE_BOOTSTRAP ON CACHE BOOL "")
+set(CLANG_BOOTSTRAP_CMAKE_ARGS
+  ${EXTRA_ARGS}
+  -C ${CMAKE_CURRENT_LIST_DIR}/Fuchsia-stage2.cmake
+  CACHE STRING "")