diff --git a/clang-tools-extra/clangd/tool/ClangdMain.cpp b/clang-tools-extra/clangd/tool/ClangdMain.cpp
--- a/clang-tools-extra/clangd/tool/ClangdMain.cpp
+++ b/clang-tools-extra/clangd/tool/ClangdMain.cpp
@@ -320,7 +320,7 @@
     "lit-test",
     cat(Misc),
     desc("Abbreviation for -input-style=delimited -pretty -sync "
-         "-enable-test-scheme -log=verbose. "
+         "-enable-test-scheme -enable-config=0 -log=verbose. "
          "Intended to simplify lit tests"),
     init(false),
     Hidden,
@@ -427,6 +427,20 @@
     Hidden,
 };
 
+opt<bool> EnableConfig{
+    "enable-config",
+    cat(Misc),
+    desc(
+        "Read user and project configuration from YAML files.\n"
+        "Project config is from a .clangd file in the project directory.\n"
+        "User config is from clangd/config.yaml in the following directories:\n"
+        "\tWindows: %USERPROFILE%\\AppData\\Local\n"
+        "\tMac OS: ~/Library/Preferences/\n"
+        "\tOthers: $XDG_CONFIG_HOME, usually ~/.config\n"
+        "Configuration is documented at https://clangd.llvm.org/config.html"),
+    init(false),
+};
+
 /// Supports a test URI scheme with relaxed constraints for lit tests.
 /// The path in a test URI will be combined with a platform-specific fake
 /// directory to form an absolute path. For example, test:///a.cpp is resolved
@@ -510,6 +524,9 @@
     InputStyle = JSONStreamStyle::Delimited;
     LogLevel = Logger::Verbose;
     PrettyPrint = true;
+    // Disable config system by default to avoid external reads.
+    if (!EnableConfig.getNumOccurrences())
+      EnableConfig = false;
     // Disable background index on lit tests by default to prevent disk writes.
     if (!EnableBackgroundIndex.getNumOccurrences())
       EnableBackgroundIndex = false;
@@ -677,6 +694,23 @@
   CCOpts.RunParser = CodeCompletionParse;
 
   RealThreadsafeFS TFS;
+  std::unique_ptr<config::Provider> Config;
+  if (EnableConfig) {
+    std::vector<std::unique_ptr<config::Provider>> ProviderStack;
+    ProviderStack.push_back(
+        config::Provider::fromAncestorRelativeYAMLFiles(".clangd", TFS));
+    llvm::SmallString<256> UserConfig;
+    if (llvm::sys::path::user_config_directory(UserConfig)) {
+      llvm::sys::path::append(UserConfig, "clangd", "config.yaml");
+      vlog("User config file is {0}", UserConfig);
+      ProviderStack.push_back(config::Provider::fromYAMLFile(UserConfig, TFS));
+    } else {
+      elog("Couldn't determine user config file, not loading");
+    }
+    Config = config::Provider::combine(std::move(ProviderStack));
+    Opts.ConfigProvider = Config.get();
+  }
+
   // Initialize and run ClangdLSPServer.
   // Change stdin to binary to not lose \r\n on windows.
   llvm::sys::ChangeStdinToBinary();