Index: cmake/caches/Fuchsia-stage2.cmake
===================================================================
--- cmake/caches/Fuchsia-stage2.cmake
+++ cmake/caches/Fuchsia-stage2.cmake
@@ -53,6 +53,25 @@
   set(RUNTIMES_${target}-fuchsia_SANITIZER_USE_COMPILER_RT ON CACHE BOOL "")
 endforeach()
 
+list(APPEND LLVM_RUNTIME_TARGETS "x86_64-fuchsia-asan=x86_64-fuchsia" "aarch64-fuchsia-asan=aarch64-fuchsia")
+foreach(target x86_64;aarch64)
+  set(RUNTIMES_${target}-fuchsia-asan_CMAKE_BUILD_WITH_INSTALL_RPATH ON CACHE BOOL "")
+  set(RUNTIMES_${target}-fuchsia-asan_CMAKE_SYSROOT ${FUCHSIA_${target}_SYSROOT} CACHE PATH "")
+  set(RUNTIMES_${target}-fuchsia-asan_CMAKE_SYSTEM_NAME Fuchsia CACHE STRING "")
+  set(RUNTIMES_${target}-fuchsia-asan_LLVM_USE_SANITIZER Address CACHE STRING "")
+  set(RUNTIMES_${target}-fuchsia-asan_LLVM_BUILD_COMPILER_RT OFF CACHE BOOL "")
+  set(RUNTIMES_${target}-fuchsia-asan_LLVM_RUNTIMES_PREFIX "${target}-fuchsia/asan" CACHE STRING "")
+  set(RUNTIMES_${target}-fuchsia-asan_UNIX 1 CACHE BOOL "")
+  set(RUNTIMES_${target}-fuchsia-asan_LLVM_ENABLE_LIBCXX ON CACHE BOOL "")
+  set(RUNTIMES_${target}-fuchsia-asan_LIBUNWIND_USE_COMPILER_RT ON CACHE BOOL "")
+  set(RUNTIMES_${target}-fuchsia-asan_LIBCXXABI_USE_COMPILER_RT ON CACHE BOOL "")
+  set(RUNTIMES_${target}-fuchsia-asan_LIBCXXABI_USE_LLVM_UNWINDER ON CACHE BOOL "")
+  set(RUNTIMES_${target}-fuchsia-asan_LIBCXXABI_ENABLE_STATIC OFF CACHE BOOL "")
+  set(RUNTIMES_${target}-fuchsia-asan_LIBCXX_USE_COMPILER_RT ON CACHE BOOL "")
+  set(RUNTIMES_${target}-fuchsia-asan_LIBCXX_ABI_VERSION 2 CACHE STRING "")
+  set(RUNTIMES_${target}-fuchsia-asan_LIBCXX_ENABLE_STATIC OFF CACHE BOOL "")
+endforeach()
+
 # Setup toolchain.
 set(LLVM_INSTALL_TOOLCHAIN_ONLY ON CACHE BOOL "")
 set(LLVM_TOOLCHAIN_TOOLS