Index: ELF/Config.h
===================================================================
--- ELF/Config.h
+++ ELF/Config.h
@@ -93,6 +93,7 @@
   ELFKind EKind = ELFNoneKind;
   uint16_t EMachine = llvm::ELF::EM_NONE;
   uint64_t EntryAddr = -1;
+  unsigned CGThreads;
   unsigned LtoO;
   unsigned Optimize;
 };
Index: ELF/Driver.cpp
===================================================================
--- ELF/Driver.cpp
+++ ELF/Driver.cpp
@@ -308,6 +308,7 @@
   Config->LtoO = getInteger(Args, OPT_lto_O, 2);
   if (Config->LtoO > 3)
     error("invalid optimization level for LTO: " + getString(Args, OPT_lto_O));
+  Config->CGThreads = getInteger(Args, OPT_jobs, 1);
 
   Config->ZExecStack = hasZOption(Args, "execstack");
   Config->ZNodelete = hasZOption(Args, "nodelete");
Index: ELF/LTO.h
===================================================================
--- ELF/LTO.h
+++ ELF/LTO.h
@@ -37,18 +37,19 @@
 class BitcodeCompiler {
 public:
   void add(BitcodeFile &F);
-  std::unique_ptr<InputFile> compile();
+  std::vector<std::unique_ptr<InputFile>> compile();
 
   BitcodeCompiler()
       : Combined(new llvm::Module("ld-temp.o", Context)), Mover(*Combined) {}
 
 private:
+  std::vector<std::unique_ptr<InputFile>> runSplitCodegen();
   llvm::TargetMachine *getTargetMachine();
 
   llvm::LLVMContext Context;
   std::unique_ptr<llvm::Module> Combined;
   llvm::IRMover Mover;
-  SmallString<0> OwningData;
+  std::vector<SmallString<0>> OwningData;
   std::unique_ptr<MemoryBuffer> MB;
   llvm::StringSet<> InternalizedSyms;
 };
Index: ELF/LTO.cpp
===================================================================
--- ELF/LTO.cpp
+++ ELF/LTO.cpp
@@ -16,6 +16,7 @@
 #include "llvm/Analysis/TargetTransformInfo.h"
 #include "llvm/Bitcode/ReaderWriter.h"
 #include "llvm/CodeGen/CommandFlags.h"
+#include "llvm/CodeGen/ParallelCG.h"
 #include "llvm/IR/LegacyPassManager.h"
 #include "llvm/Linker/IRMover.h"
 #include "llvm/Support/StringSaver.h"
@@ -33,10 +34,12 @@
 using namespace lld::elf;
 
 // This is for use when debugging LTO.
-static void saveLtoObjectFile(StringRef Buffer) {
+static void saveLtoObjectFile(StringRef Buffer, unsigned I, bool Many) {
   std::error_code EC;
-  raw_fd_ostream OS(Config->OutputFile.str() + ".lto.o", EC,
-                    sys::fs::OpenFlags::F_None);
+  SmallString<128> FileName = Config->OutputFile;
+  FileName += (Many) ? utostr(I) : "";
+  FileName += ".lto.o";
+  raw_fd_ostream OS(FileName, EC, sys::fs::OpenFlags::F_None);
   check(EC);
   OS << Buffer;
 }
@@ -136,9 +139,63 @@
   GV.setLinkage(GlobalValue::InternalLinkage);
 }
 
+static SubtargetFeatures getFeatures(Triple &TheTriple) {
+  SubtargetFeatures Features;
+  Features.getDefaultSubtargetFeatures(TheTriple);
+  for (const std::string &A : MAttrs)
+    Features.AddFeature(A);
+  return Features;
+}
+
+static CodeGenOpt::Level getCGOptLevel() {
+  switch (Config->LtoO) {
+  case 0:
+    return CodeGenOpt::None;
+  case 1:
+    return CodeGenOpt::Less;
+  case 2:
+    return CodeGenOpt::Default;
+  case 3:
+    return CodeGenOpt::Aggressive;
+  }
+  llvm_unreachable("Invalid optimization level");
+}
+
+std::vector<std::unique_ptr<InputFile>> BitcodeCompiler::runSplitCodegen() {
+  unsigned NumThreads = (Config->CGThreads >= 1) ? Config->CGThreads : 1;
+  OwningData.resize(NumThreads);
+
+  std::list<raw_svector_ostream> OSs;
+  std::vector<raw_pwrite_stream *> OSPtrs;
+  for (SmallString<0> &Obj : OwningData) {
+    OSs.emplace_back(Obj);
+    OSPtrs.push_back(&OSs.back());
+  }
+
+  std::string MCpu;
+  Triple TheTriple(Combined->getTargetTriple());
+  SubtargetFeatures Features = getFeatures(TheTriple);
+  splitCodeGen(std::move(Combined), OSPtrs, {}, MCpu, Features.getString(),
+               InitTargetOptionsFromCodeGenFlags(),
+               Config->Pic ? Reloc::PIC_ : Reloc::Static, CodeModel::Default,
+               getCGOptLevel());
+
+  std::vector<std::unique_ptr<InputFile>> ObjFiles;
+  for (SmallString<0> &Obj : OwningData) {
+    ObjFiles.push_back(createObjectFile(
+        MemoryBufferRef(Obj, "LLD-INTERNAL-combined-lto-object")));
+  }
+
+  if (Config->SaveTemps)
+    for (unsigned I = 0; I < NumThreads; ++I)
+      saveLtoObjectFile(OwningData[I], I, NumThreads > 1);
+
+  return ObjFiles;
+}
+
 // Merge all the bitcode files we have seen, codegen the result
 // and return the resulting ObjectFile.
-std::unique_ptr<InputFile> BitcodeCompiler::compile() {
+std::vector<std::unique_ptr<InputFile>> BitcodeCompiler::compile() {
   for (const auto &Name : InternalizedSyms) {
     GlobalValue *GV = Combined->getNamedValue(Name.first());
     assert(GV);
@@ -151,17 +208,7 @@
   std::unique_ptr<TargetMachine> TM(getTargetMachine());
   runLTOPasses(*Combined, *TM);
 
-  raw_svector_ostream OS(OwningData);
-  legacy::PassManager CodeGenPasses;
-  if (TM->addPassesToEmitFile(CodeGenPasses, OS,
-                              TargetMachine::CGFT_ObjectFile))
-    fatal("failed to setup codegen");
-  CodeGenPasses.run(*Combined);
-  MB = MemoryBuffer::getMemBuffer(OwningData,
-                                  "LLD-INTERNAL-combined-lto-object", false);
-  if (Config->SaveTemps)
-    saveLtoObjectFile(MB->getBuffer());
-  return createObjectFile(*MB);
+  return runSplitCodegen();
 }
 
 TargetMachine *BitcodeCompiler::getTargetMachine() {
Index: ELF/Options.td
===================================================================
--- ELF/Options.td
+++ ELF/Options.td
@@ -233,7 +233,9 @@
 // Aliases for ignored options
 def alias_version_script_version_script : Joined<["--"], "version-script=">, Alias<version_script>;
 
-// Debugging/developer options
+// LTO-related options.
+def jobs : Joined<["--"], "jobs=">,
+  HelpText<"Number of threads to run codegen">;
 def disable_verify : Flag<["-"], "disable-verify">;
 def mllvm : Separate<["-"], "mllvm">;
 def save_temps : Flag<["-"], "save-temps">;
Index: ELF/SymbolTable.cpp
===================================================================
--- ELF/SymbolTable.cpp
+++ ELF/SymbolTable.cpp
@@ -110,24 +110,26 @@
   Lto.reset(new BitcodeCompiler);
   for (const std::unique_ptr<BitcodeFile> &F : BitcodeFiles)
     Lto->add(*F);
-  std::unique_ptr<InputFile> IF = Lto->compile();
-  ObjectFile<ELFT> *Obj = cast<ObjectFile<ELFT>>(IF.release());
-
-  // Replace bitcode symbols.
-  llvm::DenseSet<StringRef> DummyGroups;
-  Obj->parse(DummyGroups);
-  for (SymbolBody *Body : Obj->getNonLocalSymbols()) {
-    Symbol *Sym = insert(Body);
-    Sym->Body->setUsedInRegularObj();
-    if (Sym->Body->isShared())
-      Sym->Body->MustBeInDynSym = true;
-    if (Sym->Body->MustBeInDynSym)
-      Body->MustBeInDynSym = true;
-    if (!Sym->Body->isUndefined() && Body->isUndefined())
-      continue;
-    Sym->Body = Body;
+  std::vector<std::unique_ptr<InputFile>> IFs = Lto->compile();
+  for (auto &IF : IFs) {
+    ObjectFile<ELFT> *Obj = cast<ObjectFile<ELFT>>(IF.release());
+
+    // Replace bitcode symbols.
+    llvm::DenseSet<StringRef> DummyGroups;
+    Obj->parse(DummyGroups);
+    for (SymbolBody *Body : Obj->getNonLocalSymbols()) {
+      Symbol *Sym = insert(Body);
+      Sym->Body->setUsedInRegularObj();
+      if (Sym->Body->isShared())
+        Sym->Body->MustBeInDynSym = true;
+      if (Sym->Body->MustBeInDynSym)
+        Body->MustBeInDynSym = true;
+      if (!Sym->Body->isUndefined() && Body->isUndefined())
+        continue;
+      Sym->Body = Body;
+    }
+    ObjectFiles.emplace_back(Obj);
   }
-  ObjectFiles.emplace_back(Obj);
 }
 
 // Add an undefined symbol.