[libc++] Provide a default LLVM_PATH when building standalone
Since we require that libc++ is built as part of the monorepo layout, we
can assume the path of the rest of LLVM and avoid requiring that LLVM_PATH
be set explicitly.
Cr-Mirrored-From: https://chromium.googlesource.com/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 09943e8de1586dd7f28aa24879fd68717a859588
diff --git a/cmake/Modules/HandleOutOfTreeLLVM.cmake b/cmake/Modules/HandleOutOfTreeLLVM.cmake
index 757450a..d488b8e 100644
--- a/cmake/Modules/HandleOutOfTreeLLVM.cmake
+++ b/cmake/Modules/HandleOutOfTreeLLVM.cmake
@@ -1,3 +1,7 @@
+if (NOT DEFINED LLVM_PATH)
+ set(LLVM_PATH ${CMAKE_CURRENT_LIST_DIR}/../../../llvm CACHE PATH "" FORCE)
+endif()
+
if(NOT IS_DIRECTORY ${LLVM_PATH})
message(FATAL_ERROR
"The provided LLVM_PATH (${LLVM_PATH}) is not a valid directory. Note that "