Index: clangd/ClangdLSPServer.cpp
===================================================================
--- clangd/ClangdLSPServer.cpp
+++ clangd/ClangdLSPServer.cpp
@@ -418,6 +418,18 @@
 
     reparseOpenedFiles();
   }
+
+  // Update to the compilation database.
+  if (Settings.compilationDatabaseChanges) {
+    const auto &CompileCommandUpdates = *Settings.compilationDatabaseChanges;
+    for (const auto &Entry : CompileCommandUpdates) {
+      NonCachedCDB.overrideCompilationCommandForFile(Entry.first,
+                                                     std::move(Entry.second));
+    }
+    CDB.clear();
+
+    reparseOpenedFiles();
+  }
 }
 
 ClangdLSPServer::ClangdLSPServer(JSONOutput &Out,
Index: clangd/Protocol.h
===================================================================
--- clangd/Protocol.h
+++ clangd/Protocol.h
@@ -424,6 +424,10 @@
 /// since the data received is described as 'any' type in LSP.
 struct ClangdConfigurationParamsChange {
   llvm::Optional<std::string> compilationDatabasePath;
+
+  // The changes that happened to the compilation database.
+  llvm::Optional<std::map<std::string, std::vector<std::string>>>
+      compilationDatabaseChanges;
 };
 bool fromJSON(const llvm::json::Value &, ClangdConfigurationParamsChange &);
 
Index: clangd/Protocol.cpp
===================================================================
--- clangd/Protocol.cpp
+++ clangd/Protocol.cpp
@@ -595,7 +595,8 @@
 bool fromJSON(const json::Value &Params,
               ClangdConfigurationParamsChange &CCPC) {
   json::ObjectMapper O(Params);
-  return O && O.map("compilationDatabasePath", CCPC.compilationDatabasePath);
+  return O && O.map("compilationDatabasePath", CCPC.compilationDatabasePath) &&
+         O.map("compilationDatabaseChanges", CCPC.compilationDatabaseChanges);
 }
 
 } // namespace clangd
Index: test/clangd/did-change-configuration-params.test
===================================================================
--- /dev/null
+++ test/clangd/did-change-configuration-params.test
@@ -0,0 +1,50 @@
+# RUN: clangd -lit-test < %s | FileCheck -strict-whitespace %s
+{"jsonrpc":"2.0","id":0,"method":"initialize","params":{"processId":123,"rootPath":"clangd","capabilities":{},"trace":"off"}}
+---
+{"jsonrpc":"2.0","method":"textDocument/didOpen","params":{"textDocument":{"uri":"test:///foo.c","languageId":"c","version":1,"text":"int main() { int i; return i; }"}}}
+#      CHECK:  "method": "textDocument/publishDiagnostics",
+# CHECK-NEXT:  "params": {
+# CHECK-NEXT:    "diagnostics": [],
+# CHECK-NEXT:    "uri": "file://{{.*}}/foo.c"
+# CHECK-NEXT:  }
+---
+{"jsonrpc":"2.0","method":"textDocument/didOpen","params":{"textDocument":{"uri":"test:///bar.c","languageId":"c","version":1,"text":"int main() { int i; return i; }"}}}
+#      CHECK:  "method": "textDocument/publishDiagnostics",
+# CHECK-NEXT:  "params": {
+# CHECK-NEXT:    "diagnostics": [],
+# CHECK-NEXT:    "uri": "file://{{.*}}/bar.c"
+# CHECK-NEXT:  }
+---
+{"jsonrpc":"2.0","method":"workspace/didChangeConfiguration","params":{"settings":{"compilationDatabaseChanges":{"/clangd-test/foo.c": ["clang", "-c", "foo.c", "-Wall", "-Werror"]}}}}
+#      CHECK:  "method": "textDocument/publishDiagnostics",
+# CHECK-NEXT:  "params": {
+# CHECK-NEXT:    "diagnostics": [
+# CHECK-NEXT:      {
+# CHECK-NEXT:        "message": "variable 'i' is uninitialized when used here",
+# CHECK-NEXT:        "range": {
+# CHECK-NEXT:          "end": {
+# CHECK-NEXT:            "character": 28,
+# CHECK-NEXT:            "line": 0
+# CHECK-NEXT:          },
+# CHECK-NEXT:          "start": {
+# CHECK-NEXT:            "character": 27,
+# CHECK-NEXT:            "line": 0
+# CHECK-NEXT:          }
+# CHECK-NEXT:        },
+# CHECK-NEXT:        "severity": 1
+# CHECK-NEXT:      }
+# CHECK-NEXT:    ],
+# CHECK-NEXT:    "uri": "file://{{.*}}/foo.c"
+# CHECK-NEXT:  }
+
+#      CHECK:  "method": "textDocument/publishDiagnostics",
+# CHECK-NEXT:  "params": {
+# CHECK-NEXT:    "diagnostics": [],
+# CHECK-NEXT:    "uri": "file://{{.*}}/bar.c"
+# CHECK-NEXT:  }
+---
+{"jsonrpc":"2.0","id":5,"method":"shutdown"}
+---
+{"jsonrpc":"2.0":"method":"exit"}
+
+