Index: cmake/caches/Fuchsia-stage2.cmake
===================================================================
--- cmake/caches/Fuchsia-stage2.cmake
+++ cmake/caches/Fuchsia-stage2.cmake
@@ -7,7 +7,7 @@
 
 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_TOOL_CLANG_TOOLS_EXTRA_BUILD ON CACHE BOOL "")
 set(LLVM_ENABLE_ZLIB ON CACHE BOOL "")
 set(LLVM_ENABLE_BACKTRACES OFF CACHE BOOL "")
 set(LLVM_EXTERNALIZE_DEBUGINFO ON CACHE BOOL "")
@@ -27,11 +27,23 @@
 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 ${FUCHSIA_SYSROOT} CACHE STRING "")
-set(BUILTINS_aarch64-fuchsia-none_CMAKE_SYSTEM_NAME Fuchsia CACHE STRING "")
+set(LLVM_BUILTIN_TARGETS "default;x86_64-unknown-fuchsia;aarch64-unknown-fuchsia" CACHE STRING "")
+foreach(target x86_64;aarch64)
+  set(BUILTINS_${target}-unknown-fuchsia_CMAKE_SYSROOT ${FUCHSIA_${target}_SYSROOT} CACHE PATH "")
+  set(BUILTINS_${target}-unknown-fuchsia_CMAKE_SYSTEM_NAME Fuchsia CACHE STRING "")
+endforeach()
+
+set(LLVM_RUNTIME_TARGETS "default;x86_64-unknown-fuchsia;aarch64-unknown-fuchsia" CACHE STRING "")
+foreach(target x86_64;aarch64)
+  set(RUNTIMES_${target}-unknown-fuchsia_CMAKE_SYSROOT ${FUCHSIA_${target}_SYSROOT} CACHE PATH "")
+  set(RUNTIMES_${target}-unknown-fuchsia_CMAKE_SYSTEM_NAME Fuchsia CACHE STRING "")
+  set(RUNTIMES_${target}-unknown-fuchsia_UNIX 1 CACHE BOOL "")
+  set(RUNTIMES_${target}-unknown-fuchsia_LLVM_ENABLE_LIBCXX ON CACHE BOOL "")
+  set(RUNTIMES_${target}-unknown-fuchsia_LIBUNWIND_USE_COMPILER_RT ON CACHE BOOL "")
+  set(RUNTIMES_${target}-unknown-fuchsia_LIBCXXABI_USE_COMPILER_RT ON CACHE BOOL "")
+  set(RUNTIMES_${target}-unknown-fuchsia_LIBCXXABI_USE_LLVM_UNWINDER ON CACHE BOOL "")
+  set(RUNTIMES_${target}-unknown-fuchsia_LIBCXX_USE_COMPILER_RT ON CACHE BOOL "")
+endforeach()
 
 # Setup toolchain.
 set(LLVM_INSTALL_TOOLCHAIN_ONLY ON CACHE BOOL "")
@@ -61,8 +73,9 @@
   LTO
   clang-format
   clang-headers
-  builtins-x86_64-fuchsia-none
-  builtins-aarch64-fuchsia-none
+  clang-tidy
+  clangd
+  builtins
   runtimes
   ${LLVM_TOOLCHAIN_TOOLS}
   CACHE STRING "")
Index: cmake/caches/Fuchsia.cmake
===================================================================
--- cmake/caches/Fuchsia.cmake
+++ cmake/caches/Fuchsia.cmake
@@ -38,9 +38,11 @@
   install-distribution
   clang CACHE STRING "")
 
-if(FUCHSIA_SYSROOT)
-  set(EXTRA_ARGS -DFUCHSIA_SYSROOT=${FUCHSIA_SYSROOT})
-endif()
+foreach(target x86_64;aarch64)
+  if(FUCHSIA_${target}_SYSROOT)
+    list(APPEND EXTRA_ARGS -DFUCHSIA_${target}_SYSROOT=${FUCHSIA_${target}_SYSROOT})
+  endif()
+endforeach()
 
 # Setup the bootstrap build.
 set(CLANG_ENABLE_BOOTSTRAP ON CACHE BOOL "")