diff --git a/clang-tools-extra/clangd/FindSymbols.cpp b/clang-tools-extra/clangd/FindSymbols.cpp
--- a/clang-tools-extra/clangd/FindSymbols.cpp
+++ b/clang-tools-extra/clangd/FindSymbols.cpp
@@ -247,6 +247,10 @@
   enum class VisitKind { No, OnlyDecl, OnlyChildren, DeclAndChildren };
 
   void traverseDecl(Decl *D, std::vector<DocumentSymbol> &Results) {
+    // Skip symbols which do not originate from the main file.
+    if (!isInsideMainFile(D->getLocation(), AST.getSourceManager()))
+      return;
+
     if (auto *Templ = llvm::dyn_cast<TemplateDecl>(D)) {
       // TemplatedDecl might be null, e.g. concepts.
       if (auto *TD = Templ->getTemplatedDecl())
diff --git a/clang-tools-extra/clangd/unittests/FindSymbolsTests.cpp b/clang-tools-extra/clangd/unittests/FindSymbolsTests.cpp
--- a/clang-tools-extra/clangd/unittests/FindSymbolsTests.cpp
+++ b/clang-tools-extra/clangd/unittests/FindSymbolsTests.cpp
@@ -523,11 +523,13 @@
       }
       )cpp";
   TU.Code = R"cpp(
+      int i; // declaration to finish preamble
       #include "bar.h"
       int test() {
       }
       )cpp";
-  EXPECT_THAT(getSymbols(TU.build()), ElementsAre(WithName("test")));
+  EXPECT_THAT(getSymbols(TU.build()),
+              ElementsAre(WithName("i"), WithName("test")));
 }
 
 TEST(DocumentSymbols, Template) {