diff --git a/clang-tools-extra/clangd/ClangdServer.cpp b/clang-tools-extra/clangd/ClangdServer.cpp
--- a/clang-tools-extra/clangd/ClangdServer.cpp
+++ b/clang-tools-extra/clangd/ClangdServer.cpp
@@ -31,6 +31,7 @@
 #include "clang/Tooling/Core/Replacement.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/Optional.h"
+#include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/ScopeExit.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/Errc.h"
@@ -60,11 +61,17 @@
       FIndex->updatePreamble(Path, Ctx, std::move(PP), CanonIncludes);
   }
 
-  void onMainAST(PathRef Path, ParsedAST &AST) override {
+  void onMainAST(PathRef Path, ParsedAST &AST,
+                 llvm::function_ref<void(PublishResults)> Publish) override {
     if (FIndex)
       FIndex->updateMain(Path, AST);
-    if (SemanticHighlighting)
-      DiagConsumer.onHighlightingsReady(Path, getSemanticHighlightings(AST));
+
+    if (!SemanticHighlighting)
+      return;
+    auto Highlightings = getSemanticHighlightings(AST);
+    Publish([&]() {
+      DiagConsumer.onHighlightingsReady(Path, std::move(Highlightings));
+    });
   }
 
   void onDiagnostics(PathRef File, std::vector<Diag> Diags) override {
diff --git a/clang-tools-extra/clangd/TUScheduler.h b/clang-tools-extra/clangd/TUScheduler.h
--- a/clang-tools-extra/clangd/TUScheduler.h
+++ b/clang-tools-extra/clangd/TUScheduler.h
@@ -15,6 +15,7 @@
 #include "Threading.h"
 #include "index/CanonicalIncludes.h"
 #include "llvm/ADT/Optional.h"
+#include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
 #include <future>
@@ -88,6 +89,7 @@
   BuildDetails Details;
 };
 
+
 class ParsingCallbacks {
 public:
   virtual ~ParsingCallbacks() = default;
@@ -98,6 +100,10 @@
   virtual void onPreambleAST(PathRef Path, ASTContext &Ctx,
                              std::shared_ptr<clang::Preprocessor> PP,
                              const CanonicalIncludes &) {}
+  /// A function that is run under the critical section guarding against races
+  /// when closing the files.
+  using PublishResults = llvm::function_ref<void()>;
+
   /// Called on the AST built for the file itself. Note that preamble AST nodes
   /// are not deserialized and should be processed in the onPreambleAST call
   /// instead.
@@ -108,7 +114,14 @@
   /// etc. Clients are expected to process only the AST nodes from the main file
   /// in this callback (obtained via ParsedAST::getLocalTopLevelDecls) to obtain
   /// optimal performance.
-  virtual void onMainAST(PathRef Path, ParsedAST &AST) {}
+  ///
+  /// This callback is run on a worker thread and if we need to send results of
+  /// processing AST to the users, we might run into a race condition with file
+  /// removal. To avoid the race condition, send the results by running \p
+  /// Publish. That would ensure publishing the results is either sequenced
+  /// before removing the file or does not happen at all.
+  virtual void onMainAST(PathRef Path, ParsedAST &AST,
+                         llvm::function_ref<void(PublishResults)> Publish) {}
 
   /// Called whenever the diagnostics for \p File are produced.
   virtual void onDiagnostics(PathRef File, std::vector<Diag> Diags) {}
diff --git a/clang-tools-extra/clangd/TUScheduler.cpp b/clang-tools-extra/clangd/TUScheduler.cpp
--- a/clang-tools-extra/clangd/TUScheduler.cpp
+++ b/clang-tools-extra/clangd/TUScheduler.cpp
@@ -486,13 +486,22 @@
     // spam us with updates.
     // Note *AST can still be null if buildAST fails.
     if (*AST) {
-      {
+      // Results from the worker thread should only be published if the file was
+      // not removed. This callback ensures the passed operation is not racing
+      // with file removal.
+      auto Publish = [&](ParsingCallbacks::PublishResults Action) {
         std::lock_guard<std::mutex> Lock(DiagsMu);
         if (ReportDiagnostics)
-          Callbacks.onDiagnostics(FileName, (*AST)->getDiagnostics());
-      }
+          Action();
+      };
+
+      // Publish diagnostics.
+      Publish([&]() {
+        Callbacks.onDiagnostics(FileName, (*AST)->getDiagnostics());
+      });
+
       trace::Span Span("Running main AST callback");
-      Callbacks.onMainAST(FileName, **AST);
+      Callbacks.onMainAST(FileName, **AST, Publish);
       DiagsWereReported = true;
     }
     // Stash the AST in the cache for further use.