diff --git a/clang-tools-extra/clang-tidy/ClangTidy.cpp b/clang-tools-extra/clang-tidy/ClangTidy.cpp
--- a/clang-tools-extra/clang-tidy/ClangTidy.cpp
+++ b/clang-tools-extra/clang-tidy/ClangTidy.cpp
@@ -431,6 +431,87 @@
   }
 
   std::vector<std::unique_ptr<ASTConsumer>> Consumers;
+
+  if (!Context.getOptions().SystemHeaders.value_or(false) ||
+      Context.getOptions().HeaderFilterRegex.value_or("") != ".*") {
+    class TraversalScopeConsumer : public ASTConsumer {
+      void Initialize(ASTContext &Context) override {
+        // Make sure the main file ID always gets included.
+        Cache.insert(
+            std::make_pair(Context.getSourceManager().getMainFileID(), true));
+      }
+
+      bool shouldKeepDeclsFromFile(SourceManager &SM, FileID FID) {
+        auto [Item, Inserted] = Cache.try_emplace(FID, true);
+
+        // Already in cache, return cached value
+        if (!Inserted)
+          return Item->getSecond();
+
+        // Tricky cases, just asume we should include
+        if (FID.isInvalid() || FID == FileID::getSentinel())
+          return true;
+
+        // Hash value isn't strictly what we need, but it currently just returns
+        // the opaque id which is what we need. Any other way to get the ID
+        // would require modifying the FID class or type-punning.
+        auto Value = static_cast<int>(FID.getHashValue());
+        SrcMgr::SLocEntry Entry;
+        if (Value > 0) {
+          // Regular file
+          Entry = SM.getLocalSLocEntry(static_cast<unsigned>(Value));
+        } else {
+          // Module
+          bool Invalid = false;
+          Entry = SM.getLoadedSLocEntry(static_cast<unsigned>(-Value - 2),
+                                        &Invalid);
+          if (Invalid)
+            return true;
+        }
+
+        if (FilterSystem &&
+            SrcMgr::isSystem(Entry.getFile().getFileCharacteristic()))
+          return Item->second = false;
+        if (HeaderFilter)
+          return Item->second = HeaderFilter->match(Entry.getFile().getName());
+        return true;
+      }
+
+      // Gather all top level decls
+      bool HandleTopLevelDecl(DeclGroupRef DG) override {
+        for (auto *D : DG) {
+          auto &SM = D->getASTContext().getSourceManager();
+          if (!shouldKeepDeclsFromFile(
+                  SM, SM.getDecomposedExpansionLoc(D->getLocation()).first))
+            continue;
+          Decls.push_back(D);
+        }
+        return true;
+      }
+
+      // Set the contexts traversal scope to only include top-level decls.
+      void HandleTranslationUnit(ASTContext &Ctx) override {
+        Ctx.setTraversalScope(Decls);
+      }
+
+      std::optional<llvm::Regex> HeaderFilter;
+      llvm::DenseMap<clang::FileID, bool> Cache;
+      bool FilterSystem;
+      std::vector<Decl *> Decls;
+
+    public:
+      TraversalScopeConsumer(bool FilterSystem,
+                             const std::optional<std::string> &HeaderFilter)
+          : FilterSystem(FilterSystem) {
+        if (HeaderFilter && *HeaderFilter != ".*")
+          this->HeaderFilter.emplace(*HeaderFilter);
+      }
+    };
+
+    Consumers.push_back(std::make_unique<TraversalScopeConsumer>(
+        !Context.getOptions().SystemHeaders.value_or(false),
+        Context.getOptions().HeaderFilterRegex));
+  }
   if (!Checks.empty())
     Consumers.push_back(Finder->newASTConsumer());