clangd args compile-commands-dir

[dusteye]

my clangd configuration in vs code is like below:
"clangd.arguments": [
"--background-index",
"--compile-commands-dir=${workspaceFolder}/build",
"--all-scopes-completion",
"--function-arg-placeholders",
"--header-insertion=iwyu",
"--completion-style=detailed",
"-j=16",
"--query-driver=/usr/local/gcc/gcc-6.3.0/bin/g++"
],

How can i config the LspAddServer args to set compile-commands-dir for clangd to find compile_commands.json?