Index: lld/ELF/Driver.cpp
===================================================================
--- lld/ELF/Driver.cpp
+++ lld/ELF/Driver.cpp
@@ -319,6 +319,18 @@
   return Default;
 }
 
+// We need to call readSymbols() on each LazyObjectFile to let it
+// construct per-file internal data structure. Do that in parallel.
+static void readLazyObjects(ArrayRef<InputFile *> Files) {
+  std::vector<LazyObjectFile *> V;
+  for (InputFile *F : Files)
+    if (auto *Lazy = dyn_cast<LazyObjectFile>(F))
+      V.push_back(Lazy);
+
+  parallelForEach(V.begin(), V.end(),
+                  [](LazyObjectFile *F) { F->readSymbols(); });
+}
+
 void LinkerDriver::main(ArrayRef<const char *> ArgsArr, bool CanExitEarly) {
   ELFOptTable Parser;
   opt::InputArgList Args = Parser.parse(ArgsArr.slice(1));
@@ -380,6 +392,7 @@
   inferMachineType();
   setConfigs();
   checkOptions(Args);
+  readLazyObjects(Files);
   if (ErrorCount)
     return;
 
Index: lld/ELF/InputFiles.h
===================================================================
--- lld/ELF/InputFiles.h
+++ lld/ELF/InputFiles.h
@@ -226,6 +226,7 @@
   }
 
   template <class ELFT> void parse();
+  void readSymbols();
   MemoryBufferRef getBuffer();
   InputFile *fetch();
 
@@ -234,7 +235,9 @@
   template <class ELFT> std::vector<StringRef> getElfSymbols();
   std::vector<StringRef> getBitcodeSymbols();
 
+  llvm::Optional<std::vector<StringRef>> Symbols;
   bool Seen = false;
+  llvm::BumpPtrAllocator Alloc;
 };
 
 // An ArchiveFile object represents a .a file.
Index: lld/ELF/InputFiles.cpp
===================================================================
--- lld/ELF/InputFiles.cpp
+++ lld/ELF/InputFiles.cpp
@@ -984,8 +984,11 @@
   return createObjectFile(MBRef);
 }
 
+void LazyObjectFile::readSymbols() { Symbols = getSymbols(); }
+
 template <class ELFT> void LazyObjectFile::parse() {
-  for (StringRef Sym : getSymbols())
+  assert(Symbols.hasValue());
+  for (StringRef Sym : *Symbols)
     Symtab<ELFT>::X->addLazyObject(Sym, *this);
 }
 
@@ -1017,6 +1020,11 @@
 std::vector<StringRef> LazyObjectFile::getBitcodeSymbols() {
   std::unique_ptr<lto::InputFile> Obj =
       check(lto::InputFile::create(this->MB), toString(this));
+
+  // Since this function is called inside parallel_for,
+  // we want to use a per-object allocator.
+  StringSaver Saver(Alloc);
+
   std::vector<StringRef> V;
   for (const lto::InputFile::Symbol &Sym : Obj->symbols())
     if (!Sym.isUndefined())