Index: clangd/ClangdLSPServer.h
===================================================================
--- clangd/ClangdLSPServer.h
+++ clangd/ClangdLSPServer.h
@@ -50,6 +50,7 @@
   // Implement ProtocolCallbacks.
   void onInitialize(Ctx C, InitializeParams &Params) override;
   void onShutdown(Ctx C, ShutdownParams &Params) override;
+  void onExit(Ctx C, ExitParams& Params) override;
   void onDocumentDidOpen(Ctx C, DidOpenTextDocumentParams &Params) override;
   void onDocumentDidChange(Ctx C, DidChangeTextDocumentParams &Params) override;
   void onDocumentDidClose(Ctx C, DidCloseTextDocumentParams &Params) override;
Index: clangd/ClangdLSPServer.cpp
===================================================================
--- clangd/ClangdLSPServer.cpp
+++ clangd/ClangdLSPServer.cpp
@@ -56,9 +56,13 @@
 }
 
 void ClangdLSPServer::onShutdown(Ctx C, ShutdownParams &Params) {
-  IsDone = true;
+  // Before we reply, we could serialize the preambles to disk. For now, let's
+  // just say we're ready to exit.
+  C.reply("null");
 }
 
+void ClangdLSPServer::onExit(Ctx C, ExitParams &Params) { IsDone = true; }
+
 void ClangdLSPServer::onDocumentDidOpen(Ctx C,
                                         DidOpenTextDocumentParams &Params) {
   if (Params.metadata && !Params.metadata->extraFlags.empty())
Index: clangd/Protocol.h
===================================================================
--- clangd/Protocol.h
+++ clangd/Protocol.h
@@ -173,6 +173,7 @@
   }
 };
 using ShutdownParams = NoParams;
+using ExitParams = NoParams;
 
 struct InitializeParams {
   /// The process Id of the parent process that started
Index: clangd/ProtocolHandlers.h
===================================================================
--- clangd/ProtocolHandlers.h
+++ clangd/ProtocolHandlers.h
@@ -34,6 +34,7 @@
 
   virtual void onInitialize(Ctx C, InitializeParams &Params) = 0;
   virtual void onShutdown(Ctx C, ShutdownParams &Params) = 0;
+  virtual void onExit(Ctx C, ExitParams& Params) = 0;
   virtual void onDocumentDidOpen(Ctx C, DidOpenTextDocumentParams &Params) = 0;
   virtual void onDocumentDidChange(Ctx C,
                                    DidChangeTextDocumentParams &Params) = 0;
Index: clangd/ProtocolHandlers.cpp
===================================================================
--- clangd/ProtocolHandlers.cpp
+++ clangd/ProtocolHandlers.cpp
@@ -52,6 +52,7 @@
 
   Register("initialize", &ProtocolCallbacks::onInitialize);
   Register("shutdown", &ProtocolCallbacks::onShutdown);
+  Register("exit", &ProtocolCallbacks::onExit);
   Register("textDocument/didOpen", &ProtocolCallbacks::onDocumentDidOpen);
   Register("textDocument/didClose", &ProtocolCallbacks::onDocumentDidClose);
   Register("textDocument/didChange", &ProtocolCallbacks::onDocumentDidChange);
Index: test/clangd/authority-less-uri.test
===================================================================
--- test/clangd/authority-less-uri.test
+++ test/clangd/authority-less-uri.test
@@ -30,3 +30,7 @@
 Content-Length: 44
 
 {"jsonrpc":"2.0","id":3,"method":"shutdown"}
+# CHECK: {"jsonrpc":"2.0","id":3,"result":null}
+Content-Length: 33
+
+{"jsonrpc":"2.0":"method":"exit"}
Index: test/clangd/completion-priorities.test
===================================================================
--- test/clangd/completion-priorities.test
+++ test/clangd/completion-priorities.test
@@ -34,3 +34,7 @@
 Content-Length: 58
 
 {"jsonrpc":"2.0","id":4,"method":"shutdown","params":null}
+# CHECK: {"jsonrpc":"2.0","id":4,"result":null}
+Content-Length: 33
+
+{"jsonrpc":"2.0":"method":"exit"}
Index: test/clangd/completion-qualifiers.test
===================================================================
--- test/clangd/completion-qualifiers.test
+++ test/clangd/completion-qualifiers.test
@@ -16,3 +16,7 @@
 Content-Length: 44
 
 {"jsonrpc":"2.0","id":4,"method":"shutdown"}
+# CHECK: {"jsonrpc":"2.0","id":4,"result":null}
+Content-Length: 33
+
+{"jsonrpc":"2.0":"method":"exit"}
Index: test/clangd/completion-snippet.test
===================================================================
--- test/clangd/completion-snippet.test
+++ test/clangd/completion-snippet.test
@@ -52,3 +52,7 @@
 Content-Length: 44
 
 {"jsonrpc":"2.0","id":4,"method":"shutdown"}
+# CHECK: {"jsonrpc":"2.0","id":4,"result":null}
+Content-Length: 33
+
+{"jsonrpc":"2.0":"method":"exit"}
Index: test/clangd/completion.test
===================================================================
--- test/clangd/completion.test
+++ test/clangd/completion.test
@@ -52,3 +52,7 @@
 Content-Length: 44
 
 {"jsonrpc":"2.0","id":4,"method":"shutdown"}
+# CHECK: {"jsonrpc":"2.0","id":4,"result":null}
+Content-Length: 33
+
+{"jsonrpc":"2.0":"method":"exit"}
Index: test/clangd/definitions.test
===================================================================
--- test/clangd/definitions.test
+++ test/clangd/definitions.test
@@ -166,3 +166,7 @@
 Content-Length: 44
 
 {"jsonrpc":"2.0","id":3,"method":"shutdown"}
+# CHECK: {"jsonrpc":"2.0","id":3,"result":null}
+Content-Length: 33
+
+{"jsonrpc":"2.0":"method":"exit"}
Index: test/clangd/diagnostics-preamble.test
===================================================================
--- test/clangd/diagnostics-preamble.test
+++ test/clangd/diagnostics-preamble.test
@@ -13,3 +13,7 @@
 Content-Length: 58
 
 {"jsonrpc":"2.0","id":2,"method":"shutdown","params":null}
+# CHECK: {"jsonrpc":"2.0","id":2,"result":null}
+Content-Length: 33
+
+{"jsonrpc":"2.0":"method":"exit"}
Index: test/clangd/diagnostics.test
===================================================================
--- test/clangd/diagnostics.test
+++ test/clangd/diagnostics.test
@@ -15,3 +15,7 @@
 Content-Length: 44
 
 {"jsonrpc":"2.0","id":5,"method":"shutdown"}
+# CHECK: {"jsonrpc":"2.0","id":5,"result":null}
+Content-Length: 33
+
+{"jsonrpc":"2.0":"method":"exit"}
Index: test/clangd/did-change-watch-files.test
===================================================================
--- test/clangd/did-change-watch-files.test
+++ test/clangd/did-change-watch-files.test
@@ -59,3 +59,6 @@
 Content-Length: 44
 
 {"jsonrpc":"2.0","id":3,"method":"shutdown"}
+Content-Length: 33
+
+{"jsonrpc":"2.0":"method":"exit"}
Index: test/clangd/extra-flags.test
===================================================================
--- test/clangd/extra-flags.test
+++ test/clangd/extra-flags.test
@@ -18,5 +18,9 @@
 Content-Length: 44
 
 {"jsonrpc":"2.0","id":5,"method":"shutdown"}
+# CHECK: {"jsonrpc":"2.0","id":5,"result":null}
+Content-Length: 33
+
+{"jsonrpc":"2.0":"method":"exit"}
 
 
Index: test/clangd/fixits.test
===================================================================
--- test/clangd/fixits.test
+++ test/clangd/fixits.test
@@ -26,3 +26,7 @@
 Content-Length: 44
 
 {"jsonrpc":"2.0","id":3,"method":"shutdown"}
+# CHECK: {"jsonrpc":"2.0","id":3,"result":null}
+Content-Length: 33
+
+{"jsonrpc":"2.0":"method":"exit"}
Index: test/clangd/formatting.test
===================================================================
--- test/clangd/formatting.test
+++ test/clangd/formatting.test
@@ -65,3 +65,7 @@
 Content-Length: 44
 
 {"jsonrpc":"2.0","id":6,"method":"shutdown"}
+# CHECK: {"jsonrpc":"2.0","id":6,"result":null}
+Content-Length: 33
+
+{"jsonrpc":"2.0":"method":"exit"}
Index: test/clangd/initialize-params-invalid.test
===================================================================
--- test/clangd/initialize-params-invalid.test
+++ test/clangd/initialize-params-invalid.test
@@ -20,3 +20,7 @@
 Content-Length: 44
 
 {"jsonrpc":"2.0","id":3,"method":"shutdown"}
+# CHECK: {"jsonrpc":"2.0","id":3,"result":null}
+Content-Length: 33
+
+{"jsonrpc":"2.0":"method":"exit"}
Index: test/clangd/initialize-params.test
===================================================================
--- test/clangd/initialize-params.test
+++ test/clangd/initialize-params.test
@@ -20,3 +20,7 @@
 Content-Length: 44
 
 {"jsonrpc":"2.0","id":3,"method":"shutdown"}
+# CHECK: {"jsonrpc":"2.0","id":3,"result":null}
+Content-Length: 33
+
+{"jsonrpc":"2.0":"method":"exit"}
Index: test/clangd/input-mirror.test
===================================================================
--- test/clangd/input-mirror.test
+++ test/clangd/input-mirror.test
@@ -152,3 +152,7 @@
 Content-Length: 44
 
 {"jsonrpc":"2.0","id":3,"method":"shutdown"}
+# CHECK: {"jsonrpc":"2.0","id":3,"result":null}
+Content-Length: 33
+
+{"jsonrpc":"2.0":"method":"exit"}
Index: test/clangd/signature-help.test
===================================================================
--- test/clangd/signature-help.test
+++ test/clangd/signature-help.test
@@ -40,3 +40,7 @@
 Content-Length: 49
 
 {"jsonrpc":"2.0","id":100000,"method":"shutdown"}
+# CHECK: {"jsonrpc":"2.0","id":100000,"result":null}
+Content-Length: 33
+
+{"jsonrpc":"2.0":"method":"exit"}
Index: test/clangd/unsupported-method.test
===================================================================
--- test/clangd/unsupported-method.test
+++ test/clangd/unsupported-method.test
@@ -17,3 +17,7 @@
 Content-Length: 44
 
 {"jsonrpc":"2.0","id":2,"method":"shutdown"}
+# CHECK: {"jsonrpc":"2.0","id":2,"result":null}
+Content-Length: 33
+
+{"jsonrpc":"2.0":"method":"exit"}