Index: lldb/include/lldb/Core/Module.h
===================================================================
--- lldb/include/lldb/Core/Module.h
+++ lldb/include/lldb/Core/Module.h
@@ -429,7 +429,11 @@
   /// This behaves like the other FindTypes method but allows to
   /// specify a DeclContext and a language for the type being searched
   /// for.
+  ///
+  /// \param searched_symbol_files
+  ///     Prevents one file from being visited multiple times.
   void FindTypes(llvm::ArrayRef<CompilerContext> pattern, LanguageSet languages,
+                 llvm::DenseSet<lldb_private::SymbolFile *> &searched_symbol_files,
                  TypeMap &types);
 
   lldb::TypeSP FindFirstType(const SymbolContext &sc,
Index: lldb/include/lldb/Symbol/SymbolFile.h
===================================================================
--- lldb/include/lldb/Symbol/SymbolFile.h
+++ lldb/include/lldb/Symbol/SymbolFile.h
@@ -193,9 +193,14 @@
             TypeMap &types);
 
   /// Find types specified by a CompilerContextPattern.
-  /// \param languages    Only return results in these languages.
-  virtual void FindTypes(llvm::ArrayRef<CompilerContext> pattern,
-                           LanguageSet languages, TypeMap &types);
+  /// \param languages
+  ///     Only return results in these languages.
+  /// \param searched_symbol_files
+  ///     Prevents one file from being visited multiple times.
+  virtual void
+  FindTypes(llvm::ArrayRef<CompilerContext> pattern, LanguageSet languages,
+            llvm::DenseSet<lldb_private::SymbolFile *> &searched_symbol_files,
+            TypeMap &types);
 
   virtual void
   GetMangledNamesForFunction(const std::string &scope_qualified_name,
Index: lldb/source/Core/Module.cpp
===================================================================
--- lldb/source/Core/Module.cpp
+++ lldb/source/Core/Module.cpp
@@ -1006,12 +1006,14 @@
   }
 }
 
-void Module::FindTypes(llvm::ArrayRef<CompilerContext> pattern,
-                       LanguageSet languages, TypeMap &types) {
+void Module::FindTypes(
+    llvm::ArrayRef<CompilerContext> pattern, LanguageSet languages,
+    llvm::DenseSet<lldb_private::SymbolFile *> &searched_symbol_files,
+    TypeMap &types) {
   static Timer::Category func_cat(LLVM_PRETTY_FUNCTION);
   Timer scoped_timer(func_cat, LLVM_PRETTY_FUNCTION);
   if (SymbolFile *symbols = GetSymbolFile())
-    symbols->FindTypes(pattern, languages, types);
+    symbols->FindTypes(pattern, languages, searched_symbol_files, types);
 }
 
 SymbolFile *Module::GetSymbolFile(bool can_create, Stream *feedback_strm) {
Index: lldb/source/Plugins/SymbolFile/Breakpad/SymbolFileBreakpad.h
===================================================================
--- lldb/source/Plugins/SymbolFile/Breakpad/SymbolFileBreakpad.h
+++ lldb/source/Plugins/SymbolFile/Breakpad/SymbolFileBreakpad.h
@@ -112,6 +112,7 @@
                  TypeMap &types) override;
 
   void FindTypes(llvm::ArrayRef<CompilerContext> pattern, LanguageSet languages,
+                 llvm::DenseSet<SymbolFile *> &searched_symbol_files,
                  TypeMap &types) override;
 
   llvm::Expected<TypeSystem &>
Index: lldb/source/Plugins/SymbolFile/Breakpad/SymbolFileBreakpad.cpp
===================================================================
--- lldb/source/Plugins/SymbolFile/Breakpad/SymbolFileBreakpad.cpp
+++ lldb/source/Plugins/SymbolFile/Breakpad/SymbolFileBreakpad.cpp
@@ -307,8 +307,9 @@
     uint32_t max_matches, llvm::DenseSet<SymbolFile *> &searched_symbol_files,
     TypeMap &types) {}
 
-void SymbolFileBreakpad::FindTypes(llvm::ArrayRef<CompilerContext> pattern,
-                                   LanguageSet languages, TypeMap &types) {}
+void SymbolFileBreakpad::FindTypes(
+    llvm::ArrayRef<CompilerContext> pattern, LanguageSet languages,
+    llvm::DenseSet<SymbolFile *> &searched_symbol_files, TypeMap &types) {}
 
 void SymbolFileBreakpad::AddSymbols(Symtab &symtab) {
   Log *log = GetLogIfAllCategoriesSet(LIBLLDB_LOG_SYMBOLS);
Index: lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
===================================================================
--- lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
+++ lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
@@ -150,7 +150,9 @@
   // The type in the Clang module must have the same language as the current CU.
   LanguageSet languages;
   languages.Insert(die.GetCU()->GetLanguageType());
-  dwo_module_sp->GetSymbolFile()->FindTypes(decl_context, languages, dwo_types);
+  llvm::DenseSet<SymbolFile *> searched_symbol_files;
+  dwo_module_sp->GetSymbolFile()->FindTypes(decl_context, languages,
+                                            searched_symbol_files, dwo_types);
   if (dwo_types.Empty()) {
     if (!IsClangModuleFwdDecl(die))
       return TypeSP();
@@ -161,8 +163,8 @@
     for (const auto &name_module : sym_file.getExternalTypeModules()) {
       if (!name_module.second)
         continue;
-      name_module.second->GetSymbolFile()->FindTypes(decl_context,
-                                                     languages, dwo_types);
+      name_module.second->GetSymbolFile()->FindTypes(
+          decl_context, languages, searched_symbol_files, dwo_types);
       if (dwo_types.GetSize())
         break;
     }
Index: lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
===================================================================
--- lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
+++ lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
@@ -190,6 +190,7 @@
 
   void FindTypes(llvm::ArrayRef<lldb_private::CompilerContext> pattern,
                  lldb_private::LanguageSet languages,
+                 llvm::DenseSet<SymbolFile *> &searched_symbol_files,
                  lldb_private::TypeMap &types) override;
 
   void GetTypes(lldb_private::SymbolContextScope *sc_scope,
Index: lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
===================================================================
--- lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
+++ lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
@@ -2366,12 +2366,10 @@
     llvm::DenseSet<lldb_private::SymbolFile *> &searched_symbol_files,
     TypeMap &types) {
   std::lock_guard<std::recursive_mutex> guard(GetModuleMutex());
-  // Make sure we haven't already searched this SymbolFile before...
-  if (searched_symbol_files.count(this))
+  // Make sure we haven't already searched this SymbolFile before.
+  if (!searched_symbol_files.insert(this).second)
     return;
 
-  searched_symbol_files.insert(this);
-
   DWARFDebugInfo *info = DebugInfo();
   if (!info)
     return;
@@ -2453,8 +2451,13 @@
   }
 }
 
-void SymbolFileDWARF::FindTypes(llvm::ArrayRef<CompilerContext> pattern,
-                                  LanguageSet languages, TypeMap &types) {
+void SymbolFileDWARF::FindTypes(
+    llvm::ArrayRef<CompilerContext> pattern, LanguageSet languages,
+    llvm::DenseSet<SymbolFile *> &searched_symbol_files, TypeMap &types) {
+  // Make sure we haven't already searched this SymbolFile before.
+  if (!searched_symbol_files.insert(this).second)
+    return;
+
   std::lock_guard<std::recursive_mutex> guard(GetModuleMutex());
   if (pattern.empty())
     return;
Index: lldb/source/Plugins/SymbolFile/NativePDB/SymbolFileNativePDB.h
===================================================================
--- lldb/source/Plugins/SymbolFile/NativePDB/SymbolFileNativePDB.h
+++ lldb/source/Plugins/SymbolFile/NativePDB/SymbolFileNativePDB.h
@@ -131,6 +131,7 @@
                  TypeMap &types) override;
 
   void FindTypes(llvm::ArrayRef<CompilerContext> pattern, LanguageSet languages,
+                 llvm::DenseSet<SymbolFile *> &searched_symbol_files,
                  TypeMap &types) override;
 
   llvm::Expected<TypeSystem &>
Index: lldb/source/Plugins/SymbolFile/NativePDB/SymbolFileNativePDB.cpp
===================================================================
--- lldb/source/Plugins/SymbolFile/NativePDB/SymbolFileNativePDB.cpp
+++ lldb/source/Plugins/SymbolFile/NativePDB/SymbolFileNativePDB.cpp
@@ -1259,8 +1259,9 @@
   FindTypesByName(name.GetStringRef(), max_matches, types);
 }
 
-void SymbolFileNativePDB::FindTypes(llvm::ArrayRef<CompilerContext> pattern,
-                                    LanguageSet languages, TypeMap &types) {}
+void SymbolFileNativePDB::FindTypes(
+    llvm::ArrayRef<CompilerContext> pattern, LanguageSet languages,
+    llvm::DenseSet<SymbolFile *> &searched_symbol_files, TypeMap &types) {}
 
 void SymbolFileNativePDB::FindTypesByName(llvm::StringRef name,
                                           uint32_t max_matches,
Index: lldb/source/Plugins/SymbolFile/PDB/SymbolFilePDB.h
===================================================================
--- lldb/source/Plugins/SymbolFile/PDB/SymbolFilePDB.h
+++ lldb/source/Plugins/SymbolFile/PDB/SymbolFilePDB.h
@@ -134,6 +134,7 @@
 
   void FindTypes(llvm::ArrayRef<lldb_private::CompilerContext> pattern,
                  lldb_private::LanguageSet languages,
+                 llvm::DenseSet<SymbolFile *> &searched_symbol_files,
                  lldb_private::TypeMap &types) override;
 
   void FindTypesByRegex(const lldb_private::RegularExpression &regex,
Index: lldb/source/Plugins/SymbolFile/PDB/SymbolFilePDB.cpp
===================================================================
--- lldb/source/Plugins/SymbolFile/PDB/SymbolFilePDB.cpp
+++ lldb/source/Plugins/SymbolFile/PDB/SymbolFilePDB.cpp
@@ -1562,9 +1562,10 @@
   }
 }
 
-void SymbolFilePDB::FindTypes(llvm::ArrayRef<CompilerContext> pattern,
-                              LanguageSet languages,
-                              lldb_private::TypeMap &types) {}
+void SymbolFilePDB::FindTypes(
+    llvm::ArrayRef<CompilerContext> pattern, LanguageSet languages,
+    llvm::DenseSet<SymbolFile *> &searched_symbol_files,
+    lldb_private::TypeMap &types) {}
 
 void SymbolFilePDB::GetTypesForPDBSymbol(const llvm::pdb::PDBSymbol &pdb_symbol,
                                          uint32_t type_mask,
Index: lldb/source/Symbol/SymbolFile.cpp
===================================================================
--- lldb/source/Symbol/SymbolFile.cpp
+++ lldb/source/Symbol/SymbolFile.cpp
@@ -134,7 +134,9 @@
     TypeMap &types) {}
 
 void SymbolFile::FindTypes(llvm::ArrayRef<CompilerContext> pattern,
-                           LanguageSet languages, TypeMap &types) {}
+                           LanguageSet languages,
+                           llvm::DenseSet<SymbolFile *> &searched_symbol_files,
+                           TypeMap &types) {}
 
 void SymbolFile::AssertModuleLock() {
   // The code below is too expensive to leave enabled in release builds. It's
Index: lldb/tools/lldb-test/lldb-test.cpp
===================================================================
--- lldb/tools/lldb-test/lldb-test.cpp
+++ lldb/tools/lldb-test/lldb-test.cpp
@@ -529,7 +529,7 @@
     Symfile.FindTypes(ConstString(Name), ContextPtr, UINT32_MAX, SearchedFiles,
                       Map);
   else
-    Module.FindTypes(parseCompilerContext(), languages, Map);
+    Module.FindTypes(parseCompilerContext(), languages, SearchedFiles, Map);
 
   outs() << formatv("Found {0} types:\n", Map.GetSize());
   StreamString Stream;