diff --git a/clang-tools-extra/clangd/test/system-include-extractor.test b/clang-tools-extra/clangd/test/system-include-extractor.test
--- a/clang-tools-extra/clangd/test/system-include-extractor.test
+++ b/clang-tools-extra/clangd/test/system-include-extractor.test
@@ -11,9 +11,12 @@
 # RUN: echo '#!/bin/sh' >> %t.dir/bin/my_driver.sh
 # RUN: echo '[ "$0" = "%t.dir/bin/my_driver.sh" ] || exit' >> %t.dir/bin/my_driver.sh
 # RUN: echo 'args="$*"' >> %t.dir/bin/my_driver.sh
+# The purpose of the three lines below is to test that the -nostdinc etc. arguments,
+# all of which are present in the command in compile_commands.json below, are passed
+# on by clang to the driver being queried (unlike most other arguments).
 # RUN: echo '[ -z "${args##*"-nostdinc"*}" ] || exit' >> %t.dir/bin/my_driver.sh
 # RUN: echo '[ -z "${args##*"-isysroot=/isysroot"*}" ] || exit' >> %t.dir/bin/my_driver.sh
-# RUN: echo 'echo " $* " | grep " --sysroot /my/sysroot/path " || exit' >> %t.dir/bin/my_driver.sh
+# RUN: echo '[ -z "${args##*"--sysroot /my/sysroot/path"*}" ] || exit' >> %t.dir/bin/my_driver.sh
 # RUN: echo 'echo line to ignore >&2' >> %t.dir/bin/my_driver.sh
 # RUN: echo 'printf "Target: arm-linux-gnueabihf\r\n" >&2' >> %t.dir/bin/my_driver.sh
 # RUN: echo 'printf "#include <...> search starts here:\r\n" >&2' >> %t.dir/bin/my_driver.sh