diff --git a/clang-tools-extra/clangd/Diagnostics.cpp b/clang-tools-extra/clangd/Diagnostics.cpp
--- a/clang-tools-extra/clangd/Diagnostics.cpp
+++ b/clang-tools-extra/clangd/Diagnostics.cpp
@@ -469,6 +469,11 @@
   }
 
   bool InsideMainFile = isInsideMainFile(Info);
+  SourceManager &SM = Info.getSourceManager();
+  if (!InsideMainFile && SM.isWrittenInBuiltinFile(Info.getLocation())) {
+    IgnoreDiagnostics::log(DiagLevel, Info);
+    return;
+  }
 
   auto FillDiagBase = [&](DiagBase &D) {
     D.Range = diagnosticRange(Info, *LangOpts);
@@ -476,8 +481,7 @@
     Info.FormatDiagnostic(Message);
     D.Message = Message.str();
     D.InsideMainFile = InsideMainFile;
-    D.File = Info.getSourceManager().getFilename(Info.getLocation());
-    auto &SM = Info.getSourceManager();
+    D.File = SM.getFilename(Info.getLocation());
     D.AbsFile = getCanonicalPath(
         SM.getFileEntryForID(SM.getFileID(Info.getLocation())), SM);
     D.Severity = DiagLevel;
@@ -500,10 +504,9 @@
       if (FixIt.RemoveRange.getBegin().isMacroID() ||
           FixIt.RemoveRange.getEnd().isMacroID())
         return false;
-      if (!isInsideMainFile(FixIt.RemoveRange.getBegin(),
-                            Info.getSourceManager()))
+      if (!isInsideMainFile(FixIt.RemoveRange.getBegin(), SM))
         return false;
-      Edits.push_back(toTextEdit(FixIt, Info.getSourceManager(), *LangOpts));
+      Edits.push_back(toTextEdit(FixIt, SM, *LangOpts));
     }
 
     llvm::SmallString<64> Message;
@@ -511,8 +514,8 @@
     if (SyntheticMessage && Info.getNumFixItHints() == 1) {
       const auto &FixIt = Info.getFixItHint(0);
       bool Invalid = false;
-      llvm::StringRef Remove = Lexer::getSourceText(
-          FixIt.RemoveRange, Info.getSourceManager(), *LangOpts, &Invalid);
+      llvm::StringRef Remove =
+          Lexer::getSourceText(FixIt.RemoveRange, SM, *LangOpts, &Invalid);
       llvm::StringRef Insert = FixIt.CodeToInsert;
       if (!Invalid) {
         llvm::raw_svector_ostream M(Message);