diff --git a/llvm/lib/Object/COFFImportFile.cpp b/llvm/lib/Object/COFFImportFile.cpp
new file mode 100644
index 0000000..37962d8
--- /dev/null
+++ b/llvm/lib/Object/COFFImportFile.cpp
@@ -0,0 +1,527 @@
+//===- COFFImportFile.cpp - COFF short import file implementation ---------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the writeImportLibrary function.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Object/COFFImportFile.h"
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/Object/Archive.h"
+#include "llvm/Object/ArchiveWriter.h"
+#include "llvm/Object/COFF.h"
+#include "llvm/Support/Error.h"
+#include "llvm/Support/Path.h"
+
+#include <cstdint>
+#include <map>
+#include <set>
+#include <string>
+#include <vector>
+
+using namespace llvm::COFF;
+using namespace llvm::object;
+using namespace llvm;
+
+namespace llvm {
+namespace object {
+
+static bool is32bit(MachineTypes Machine) {
+  switch (Machine) {
+  default:
+    llvm_unreachable("unsupported machine");
+  case IMAGE_FILE_MACHINE_AMD64:
+    return false;
+  case IMAGE_FILE_MACHINE_ARMNT:
+  case IMAGE_FILE_MACHINE_I386:
+    return true;
+  }
+}
+
+static uint16_t getImgRelRelocation(MachineTypes Machine) {
+  switch (Machine) {
+  default:
+    llvm_unreachable("unsupported machine");
+  case IMAGE_FILE_MACHINE_AMD64:
+    return IMAGE_REL_AMD64_ADDR32NB;
+  case IMAGE_FILE_MACHINE_ARMNT:
+    return IMAGE_REL_ARM_ADDR32NB;
+  case IMAGE_FILE_MACHINE_I386:
+    return IMAGE_REL_I386_DIR32NB;
+  }
+}
+
+template <class T> static void append(std::vector<uint8_t> &B, const T &Data) {
+  size_t S = B.size();
+  B.resize(S + sizeof(T));
+  memcpy(&B[S], &Data, sizeof(T));
+}
+
+static void writeStringTable(std::vector<uint8_t> &B,
+                             ArrayRef<const std::string> Strings) {
+  // The COFF string table consists of a 4-byte value which is the size of the
+  // table, including the length field itself.  This value is followed by the
+  // string content itself, which is an array of null-terminated C-style
+  // strings.  The termination is important as they are referenced to by offset
+  // by the symbol entity in the file format.
+
+  size_t Pos = B.size();
+  size_t Offset = B.size();
+
+  // Skip over the length field, we will fill it in later as we will have
+  // computed the length while emitting the string content itself.
+  Pos += sizeof(uint32_t);
+
+  for (const auto &S : Strings) {
+    B.resize(Pos + S.length() + 1);
+    strcpy(reinterpret_cast<char *>(&B[Pos]), S.c_str());
+    Pos += S.length() + 1;
+  }
+
+  // Backfill the length of the table now that it has been computed.
+  support::ulittle32_t Length(B.size() - Offset);
+  support::endian::write32le(&B[Offset], Length);
+}
+
+static ImportNameType getNameType(StringRef Sym, StringRef ExtName,
+                                  MachineTypes Machine) {
+  if (Sym != ExtName)
+    return IMPORT_NAME_UNDECORATE;
+  if (Machine == IMAGE_FILE_MACHINE_I386 && Sym.startswith("_"))
+    return IMPORT_NAME_NOPREFIX;
+  return IMPORT_NAME;
+}
+
+static Expected<std::string> replace(StringRef S, StringRef From,
+                                     StringRef To) {
+  size_t Pos = S.find(From);
+
+  // From and To may be mangled, but substrings in S may not.
+  if (Pos == StringRef::npos && From.startswith("_") && To.startswith("_")) {
+    From = From.substr(1);
+    To = To.substr(1);
+    Pos = S.find(From);
+  }
+
+  if (Pos == StringRef::npos) {
+    return make_error<StringError>(
+      StringRef(Twine(S + ": replacing '" + From +
+        "' with '" + To + "' failed").str()), object_error::parse_failed);
+  }
+
+  return (Twine(S.substr(0, Pos)) + To + S.substr(Pos + From.size())).str();
+}
+
+static const std::string NullImportDescriptorSymbolName =
+    "__NULL_IMPORT_DESCRIPTOR";
+
+namespace {
+// This class constructs various small object files necessary to support linking
+// symbols imported from a DLL.  The contents are pretty strictly defined and
+// nearly entirely static.  The details of the structures files are defined in
+// WINNT.h and the PE/COFF specification.
+class ObjectFactory {
+  using u16 = support::ulittle16_t;
+  using u32 = support::ulittle32_t;
+  MachineTypes Machine;
+  BumpPtrAllocator Alloc;
+  StringRef DLLName;
+  StringRef Library;
+  std::string ImportDescriptorSymbolName;
+  std::string NullThunkSymbolName;
+
+public:
+  ObjectFactory(StringRef S, MachineTypes M)
+      : Machine(M), DLLName(S), Library(S.drop_back(4)),
+        ImportDescriptorSymbolName(("__IMPORT_DESCRIPTOR_" + Library).str()),
+        NullThunkSymbolName(("\x7f" + Library + "_NULL_THUNK_DATA").str()) {}
+
+  // Creates an Import Descriptor.  This is a small object file which contains a
+  // reference to the terminators and contains the library name (entry) for the
+  // import name table.  It will force the linker to construct the necessary
+  // structure to import symbols from the DLL.
+  NewArchiveMember createImportDescriptor(std::vector<uint8_t> &Buffer);
+
+  // Creates a NULL import descriptor.  This is a small object file whcih
+  // contains a NULL import descriptor.  It is used to terminate the imports
+  // from a specific DLL.
+  NewArchiveMember createNullImportDescriptor(std::vector<uint8_t> &Buffer);
+
+  // Create a NULL Thunk Entry.  This is a small object file which contains a
+  // NULL Import Address Table entry and a NULL Import Lookup Table Entry.  It
+  // is used to terminate the IAT and ILT.
+  NewArchiveMember createNullThunk(std::vector<uint8_t> &Buffer);
+
+  // Create a short import file which is described in PE/COFF spec 7. Import
+  // Library Format.
+  NewArchiveMember createShortImport(StringRef Sym, uint16_t Ordinal,
+                                     ImportType Type, ImportNameType NameType);
+};
+} // namespace
+
+NewArchiveMember
+ObjectFactory::createImportDescriptor(std::vector<uint8_t> &Buffer) {
+  static const uint32_t NumberOfSections = 2;
+  static const uint32_t NumberOfSymbols = 7;
+  static const uint32_t NumberOfRelocations = 3;
+
+  // COFF Header
+  coff_file_header Header{
+      u16(Machine),
+      u16(NumberOfSections),
+      u32(0),
+      u32(sizeof(Header) + (NumberOfSections * sizeof(coff_section)) +
+          // .idata$2
+          sizeof(coff_import_directory_table_entry) +
+          NumberOfRelocations * sizeof(coff_relocation) +
+          // .idata$4
+          (DLLName.size() + 1)),
+      u32(NumberOfSymbols),
+      u16(0),
+      u16(is32bit(Machine) ? IMAGE_FILE_32BIT_MACHINE : 0),
+  };
+  append(Buffer, Header);
+
+  // Section Header Table
+  static const coff_section SectionTable[NumberOfSections] = {
+      {{'.', 'i', 'd', 'a', 't', 'a', '$', '2'},
+       u32(0),
+       u32(0),
+       u32(sizeof(coff_import_directory_table_entry)),
+       u32(sizeof(coff_file_header) + NumberOfSections * sizeof(coff_section)),
+       u32(sizeof(coff_file_header) + NumberOfSections * sizeof(coff_section) +
+           sizeof(coff_import_directory_table_entry)),
+       u32(0),
+       u16(NumberOfRelocations),
+       u16(0),
+       u32(IMAGE_SCN_ALIGN_4BYTES | IMAGE_SCN_CNT_INITIALIZED_DATA |
+           IMAGE_SCN_MEM_READ | IMAGE_SCN_MEM_WRITE)},
+      {{'.', 'i', 'd', 'a', 't', 'a', '$', '6'},
+       u32(0),
+       u32(0),
+       u32(DLLName.size() + 1),
+       u32(sizeof(coff_file_header) + NumberOfSections * sizeof(coff_section) +
+           sizeof(coff_import_directory_table_entry) +
+           NumberOfRelocations * sizeof(coff_relocation)),
+       u32(0),
+       u32(0),
+       u16(0),
+       u16(0),
+       u32(IMAGE_SCN_ALIGN_2BYTES | IMAGE_SCN_CNT_INITIALIZED_DATA |
+           IMAGE_SCN_MEM_READ | IMAGE_SCN_MEM_WRITE)},
+  };
+  append(Buffer, SectionTable);
+
+  // .idata$2
+  static const coff_import_directory_table_entry ImportDescriptor{
+      u32(0), u32(0), u32(0), u32(0), u32(0),
+  };
+  append(Buffer, ImportDescriptor);
+
+  static const coff_relocation RelocationTable[NumberOfRelocations] = {
+      {u32(offsetof(coff_import_directory_table_entry, NameRVA)), u32(2),
+       u16(getImgRelRelocation(Machine))},
+      {u32(offsetof(coff_import_directory_table_entry, ImportLookupTableRVA)),
+       u32(3), u16(getImgRelRelocation(Machine))},
+      {u32(offsetof(coff_import_directory_table_entry, ImportAddressTableRVA)),
+       u32(4), u16(getImgRelRelocation(Machine))},
+  };
+  append(Buffer, RelocationTable);
+
+  // .idata$6
+  auto S = Buffer.size();
+  Buffer.resize(S + DLLName.size() + 1);
+  memcpy(&Buffer[S], DLLName.data(), DLLName.size());
+  Buffer[S + DLLName.size()] = '\0';
+
+  // Symbol Table
+  coff_symbol16 SymbolTable[NumberOfSymbols] = {
+      {{{0, 0, 0, 0, 0, 0, 0, 0}},
+       u32(0),
+       u16(1),
+       u16(0),
+       IMAGE_SYM_CLASS_EXTERNAL,
+       0},
+      {{{'.', 'i', 'd', 'a', 't', 'a', '$', '2'}},
+       u32(0),
+       u16(1),
+       u16(0),
+       IMAGE_SYM_CLASS_SECTION,
+       0},
+      {{{'.', 'i', 'd', 'a', 't', 'a', '$', '6'}},
+       u32(0),
+       u16(2),
+       u16(0),
+       IMAGE_SYM_CLASS_STATIC,
+       0},
+      {{{'.', 'i', 'd', 'a', 't', 'a', '$', '4'}},
+       u32(0),
+       u16(0),
+       u16(0),
+       IMAGE_SYM_CLASS_SECTION,
+       0},
+      {{{'.', 'i', 'd', 'a', 't', 'a', '$', '5'}},
+       u32(0),
+       u16(0),
+       u16(0),
+       IMAGE_SYM_CLASS_SECTION,
+       0},
+      {{{0, 0, 0, 0, 0, 0, 0, 0}},
+       u32(0),
+       u16(0),
+       u16(0),
+       IMAGE_SYM_CLASS_EXTERNAL,
+       0},
+      {{{0, 0, 0, 0, 0, 0, 0, 0}},
+       u32(0),
+       u16(0),
+       u16(0),
+       IMAGE_SYM_CLASS_EXTERNAL,
+       0},
+  };
+  reinterpret_cast<StringTableOffset &>(SymbolTable[0].Name).Offset =
+      sizeof(uint32_t);
+  reinterpret_cast<StringTableOffset &>(SymbolTable[5].Name).Offset =
+      sizeof(uint32_t) + ImportDescriptorSymbolName.length() + 1;
+  reinterpret_cast<StringTableOffset &>(SymbolTable[6].Name).Offset =
+      sizeof(uint32_t) + ImportDescriptorSymbolName.length() + 1 +
+      NullImportDescriptorSymbolName.length() + 1;
+  append(Buffer, SymbolTable);
+
+  // String Table
+  writeStringTable(Buffer,
+                   {ImportDescriptorSymbolName, NullImportDescriptorSymbolName,
+                    NullThunkSymbolName});
+
+  StringRef F{reinterpret_cast<const char *>(Buffer.data()), Buffer.size()};
+  return {MemoryBufferRef(F, DLLName)};
+}
+
+NewArchiveMember
+ObjectFactory::createNullImportDescriptor(std::vector<uint8_t> &Buffer) {
+  static const uint32_t NumberOfSections = 1;
+  static const uint32_t NumberOfSymbols = 1;
+
+  // COFF Header
+  coff_file_header Header{
+      u16(Machine),
+      u16(NumberOfSections),
+      u32(0),
+      u32(sizeof(Header) + (NumberOfSections * sizeof(coff_section)) +
+          // .idata$3
+          sizeof(coff_import_directory_table_entry)),
+      u32(NumberOfSymbols),
+      u16(0),
+      u16(is32bit(Machine) ? IMAGE_FILE_32BIT_MACHINE : 0),
+  };
+  append(Buffer, Header);
+
+  // Section Header Table
+  static const coff_section SectionTable[NumberOfSections] = {
+      {{'.', 'i', 'd', 'a', 't', 'a', '$', '3'},
+       u32(0),
+       u32(0),
+       u32(sizeof(coff_import_directory_table_entry)),
+       u32(sizeof(coff_file_header) +
+           (NumberOfSections * sizeof(coff_section))),
+       u32(0),
+       u32(0),
+       u16(0),
+       u16(0),
+       u32(IMAGE_SCN_ALIGN_4BYTES | IMAGE_SCN_CNT_INITIALIZED_DATA |
+           IMAGE_SCN_MEM_READ | IMAGE_SCN_MEM_WRITE)},
+  };
+  append(Buffer, SectionTable);
+
+  // .idata$3
+  static const coff_import_directory_table_entry ImportDescriptor{
+      u32(0), u32(0), u32(0), u32(0), u32(0),
+  };
+  append(Buffer, ImportDescriptor);
+
+  // Symbol Table
+  coff_symbol16 SymbolTable[NumberOfSymbols] = {
+      {{{0, 0, 0, 0, 0, 0, 0, 0}},
+       u32(0),
+       u16(1),
+       u16(0),
+       IMAGE_SYM_CLASS_EXTERNAL,
+       0},
+  };
+  reinterpret_cast<StringTableOffset &>(SymbolTable[0].Name).Offset =
+      sizeof(uint32_t);
+  append(Buffer, SymbolTable);
+
+  // String Table
+  writeStringTable(Buffer, {NullImportDescriptorSymbolName});
+
+  StringRef F{reinterpret_cast<const char *>(Buffer.data()), Buffer.size()};
+  return {MemoryBufferRef(F, DLLName)};
+}
+
+NewArchiveMember ObjectFactory::createNullThunk(std::vector<uint8_t> &Buffer) {
+  static const uint32_t NumberOfSections = 2;
+  static const uint32_t NumberOfSymbols = 1;
+  uint32_t VASize = is32bit(Machine) ? 4 : 8;
+
+  // COFF Header
+  coff_file_header Header{
+      u16(Machine),
+      u16(NumberOfSections),
+      u32(0),
+      u32(sizeof(Header) + (NumberOfSections * sizeof(coff_section)) +
+          // .idata$5
+          VASize +
+          // .idata$4
+          VASize),
+      u32(NumberOfSymbols),
+      u16(0),
+      u16(is32bit(Machine) ? IMAGE_FILE_32BIT_MACHINE : 0),
+  };
+  append(Buffer, Header);
+
+  // Section Header Table
+  static const coff_section SectionTable[NumberOfSections] = {
+      {{'.', 'i', 'd', 'a', 't', 'a', '$', '5'},
+       u32(0),
+       u32(0),
+       u32(VASize),
+       u32(sizeof(coff_file_header) + NumberOfSections * sizeof(coff_section)),
+       u32(0),
+       u32(0),
+       u16(0),
+       u16(0),
+       u32((is32bit(Machine) ? IMAGE_SCN_ALIGN_4BYTES
+                             : IMAGE_SCN_ALIGN_8BYTES) |
+           IMAGE_SCN_CNT_INITIALIZED_DATA | IMAGE_SCN_MEM_READ |
+           IMAGE_SCN_MEM_WRITE)},
+      {{'.', 'i', 'd', 'a', 't', 'a', '$', '4'},
+       u32(0),
+       u32(0),
+       u32(VASize),
+       u32(sizeof(coff_file_header) + NumberOfSections * sizeof(coff_section) +
+           VASize),
+       u32(0),
+       u32(0),
+       u16(0),
+       u16(0),
+       u32((is32bit(Machine) ? IMAGE_SCN_ALIGN_4BYTES
+                             : IMAGE_SCN_ALIGN_8BYTES) |
+           IMAGE_SCN_CNT_INITIALIZED_DATA | IMAGE_SCN_MEM_READ |
+           IMAGE_SCN_MEM_WRITE)},
+  };
+  append(Buffer, SectionTable);
+
+  // .idata$5, ILT
+  append(Buffer, u32(0));
+  if (!is32bit(Machine))
+    append(Buffer, u32(0));
+
+  // .idata$4, IAT
+  append(Buffer, u32(0));
+  if (!is32bit(Machine))
+    append(Buffer, u32(0));
+
+  // Symbol Table
+  coff_symbol16 SymbolTable[NumberOfSymbols] = {
+      {{{0, 0, 0, 0, 0, 0, 0, 0}},
+       u32(0),
+       u16(1),
+       u16(0),
+       IMAGE_SYM_CLASS_EXTERNAL,
+       0},
+  };
+  reinterpret_cast<StringTableOffset &>(SymbolTable[0].Name).Offset =
+      sizeof(uint32_t);
+  append(Buffer, SymbolTable);
+
+  // String Table
+  writeStringTable(Buffer, {NullThunkSymbolName});
+
+  StringRef F{reinterpret_cast<const char *>(Buffer.data()), Buffer.size()};
+  return {MemoryBufferRef{F, DLLName}};
+}
+
+NewArchiveMember ObjectFactory::createShortImport(StringRef Sym,
+                                                  uint16_t Ordinal,
+                                                  ImportType ImportType,
+                                                  ImportNameType NameType) {
+  size_t ImpSize = DLLName.size() + Sym.size() + 2; // +2 for NULs
+  size_t Size = sizeof(coff_import_header) + ImpSize;
+  char *Buf = Alloc.Allocate<char>(Size);
+  memset(Buf, 0, Size);
+  char *P = Buf;
+
+  // Write short import library.
+  auto *Imp = reinterpret_cast<coff_import_header *>(P);
+  P += sizeof(*Imp);
+  Imp->Sig2 = 0xFFFF;
+  Imp->Machine = Machine;
+  Imp->SizeOfData = ImpSize;
+  if (Ordinal > 0)
+    Imp->OrdinalHint = Ordinal;
+  Imp->TypeInfo = (NameType << 2) | ImportType;
+
+  // Write symbol name and DLL name.
+  memcpy(P, Sym.data(), Sym.size());
+  P += Sym.size() + 1;
+  memcpy(P, DLLName.data(), DLLName.size());
+
+  return {MemoryBufferRef(StringRef(Buf, Size), DLLName)};
+}
+
+std::error_code writeImportLibrary(StringRef DLLName, StringRef Path,
+                                   ArrayRef<COFFShortExport> Exports,
+                                   MachineTypes Machine) {
+
+  std::vector<NewArchiveMember> Members;
+  ObjectFactory OF(llvm::sys::path::filename(DLLName), Machine);
+
+  std::vector<uint8_t> ImportDescriptor;
+  Members.push_back(OF.createImportDescriptor(ImportDescriptor));
+
+  std::vector<uint8_t> NullImportDescriptor;
+  Members.push_back(OF.createNullImportDescriptor(NullImportDescriptor));
+
+  std::vector<uint8_t> NullThunk;
+  Members.push_back(OF.createNullThunk(NullThunk));
+
+  for (COFFShortExport E : Exports) {
+    if (E.Private)
+      continue;
+
+    ImportType ImportType = IMPORT_CODE;
+    if (E.Data)
+      ImportType = IMPORT_DATA;
+    if (E.Constant)
+      ImportType = IMPORT_CONST;
+
+    StringRef SymbolName = E.isWeak() ? E.ExtName : E.Name;
+    ImportNameType NameType = getNameType(SymbolName, E.Name, Machine);
+    Expected<std::string> Name = E.ExtName.empty()
+                                     ? SymbolName
+                                     : replace(SymbolName, E.Name, E.ExtName);
+
+    if (!Name) {
+      return errorToErrorCode(Name.takeError());
+    }
+
+    Members.push_back(
+        OF.createShortImport(*Name, E.Ordinal, ImportType, NameType));
+  }
+
+  std::pair<StringRef, std::error_code> Result =
+      writeArchive(Path, Members, /*WriteSymtab*/ true, object::Archive::K_GNU,
+                   /*Deterministic*/ true, /*Thin*/ false);
+
+  return Result.second;
+}
+
+} // namespace object
+} // namespace llvm