[clangd] Fix builds after 4ddae8b941398a6579d3

(cherry picked from commit 9ffef0f24de0fc05b946e662a7b233a32ad058e3)
diff --git a/clang-tools-extra/clangd/test/CMakeLists.txt b/clang-tools-extra/clangd/test/CMakeLists.txt
index 840fe2b..d073267 100644
--- a/clang-tools-extra/clangd/test/CMakeLists.txt
+++ b/clang-tools-extra/clangd/test/CMakeLists.txt
@@ -28,14 +28,11 @@
-# Copy an empty compile_commands.json to override the compile_commands.json
-# in the top level build directory.  Or if a clangd test involves creating a
-# temporary source file in the build directory and run clangd to check it,
-# it can pick up unrecognizable command options when LLVM is built with
-# another compiler or a different version of Clang.
-  ${CMAKE_CURRENT_SOURCE_DIR}/compile_commands.json
-  ${CMAKE_CURRENT_BINARY_DIR}/compile_commands.json
+# Copy an empty compile_flags.txt to make sure tests don't pick up arbitrary
+# commands from parents.
+  ${CMAKE_CURRENT_BINARY_DIR}/compile_flags.txt
 add_lit_testsuite(check-clangd "Running the Clangd regression tests"
diff --git a/clang-tools-extra/clangd/test/compile_commands.json b/clang-tools-extra/clangd/test/compile_commands.json
deleted file mode 100644
index fe51488..0000000
--- a/clang-tools-extra/clangd/test/compile_commands.json
+++ /dev/null
@@ -1 +0,0 @@