Index: clang/cmake/caches/Fuchsia.cmake
===================================================================
--- clang/cmake/caches/Fuchsia.cmake
+++ clang/cmake/caches/Fuchsia.cmake
@@ -1,6 +1,6 @@
 # This file sets up a CMakeCache for a Fuchsia toolchain build.
 
-set(LLVM_TARGETS_TO_BUILD Native CACHE STRING "")
+set(LLVM_TARGETS_TO_BUILD X86;ARM;AArch64 CACHE STRING "")
 
 set(PACKAGE_VENDOR Fuchsia CACHE STRING "")
 
@@ -57,6 +57,38 @@
   install-distribution-stripped
   clang CACHE STRING "")
 
+if(BOOTSTRAP_CMAKE_SYSTEM_NAME)
+  string(FIND ${BOOTSTRAP_CMAKE_CXX_COMPILER_TARGET} "-" dash_index)
+  string(SUBSTRING ${BOOTSTRAP_CMAKE_CXX_COMPILER_TARGET} 0 ${dash_index} target)
+  if(STAGE2_LINUX_${target}_SYSROOT)
+    set(BUILTINS_${target}-linux-gnu_CMAKE_SYSTEM_NAME Linux CACHE STRING "")
+    set(BUILTINS_${target}-linux-gnu_CMAKE_BUILD_TYPE Release CACHE STRING "")
+    set(BUILTINS_${target}-linux-gnu_CMAKE_SYSROOT ${STAGE2_LINUX_${target}_SYSROOT} CACHE STRING "")
+    set(LLVM_BUILTIN_TARGETS "${target}-linux-gnu" CACHE STRING "")
+
+    set(RUNTIMES_${target}-linux-gnu_CMAKE_SYSTEM_NAME Linux CACHE STRING "")
+    set(RUNTIMES_${target}-linux-gnu_CMAKE_BUILD_TYPE Release CACHE STRING "")
+    set(RUNTIMES_${target}-linux-gnu_CMAKE_SYSROOT ${STAGE2_LINUX_${target}_SYSROOT} CACHE STRING "")
+    set(RUNTIMES_${target}-linux-gnu_LLVM_ENABLE_ASSERTIONS ON CACHE BOOL "")
+    set(RUNTIMES_${target}-linux-gnu_LIBUNWIND_ENABLE_SHARED OFF CACHE BOOL "")
+    set(RUNTIMES_${target}-linux-gnu_LIBUNWIND_USE_COMPILER_RT ON CACHE BOOL "")
+    set(RUNTIMES_${target}-linux-gnu_LIBUNWIND_INSTALL_LIBRARY OFF CACHE BOOL "")
+    set(RUNTIMES_${target}-linux-gnu_LIBCXXABI_USE_COMPILER_RT ON CACHE BOOL "")
+    set(RUNTIMES_${target}-linux-gnu_LIBCXXABI_ENABLE_SHARED OFF CACHE BOOL "")
+    set(RUNTIMES_${target}-linux-gnu_LIBCXXABI_USE_LLVM_UNWINDER ON CACHE BOOL "")
+    set(RUNTIMES_${target}-linux-gnu_LIBCXXABI_ENABLE_STATIC_UNWINDER ON CACHE BOOL "")
+    set(RUNTIMES_${target}-linux-gnu_LIBCXXABI_INSTALL_LIBRARY OFF CACHE BOOL "")
+    set(RUNTIMES_${target}-linux-gnu_LIBCXX_USE_COMPILER_RT ON CACHE BOOL "")
+    set(RUNTIMES_${target}-linux-gnu_LIBCXX_ENABLE_SHARED OFF CACHE BOOL "")
+    set(RUNTIMES_${target}-linux-gnu_LIBCXX_ENABLE_STATIC_ABI_LIBRARY ON CACHE BOOL "")
+    set(RUNTIMES_${target}-linux-gnu_LIBCXX_ABI_VERSION 2 CACHE STRING "")
+    set(RUNTIMES_${target}-linux-gnu_SANITIZER_CXX_ABI "libc++" CACHE STRING "")
+    set(RUNTIMES_${target}-linux-gnu_SANITIZER_CXX_ABI_INTREE ON CACHE BOOL "")
+    set(RUNTIMES_${target}-linux-gnu_COMPILER_RT_USE_BUILTINS_LIBRARY ON CACHE BOOL "")
+    set(LLVM_RUNTIME_TARGETS "${target}-linux-gnu" CACHE STRING "")
+  endif()
+endif()
+
 get_cmake_property(variableNames VARIABLES)
 foreach(variableName ${variableNames})
   if(variableName MATCHES "^STAGE2_")