8 files changed, 528 insertions, 18 deletions

diff --git a/llvm/test/tools/llvm-lipo/Inputs/arm64-slice.yaml b/llvm/test/tools/llvm-lipo/Inputs/arm64-slice.yaml
new file mode 100644
index 00000000000..5dfd4502738
--- /dev/null
+++ b/llvm/test/tools/llvm-lipo/Inputs/arm64-slice.yaml
@@ -0,0 +1,101 @@
+--- !mach-o
+FileHeader:      
+  magic:           0xFEEDFACF
+  cputype:         0x0100000C
+  cpusubtype:      0x00000000
+  filetype:        0x00000001
+  ncmds:           4
+  sizeofcmds:      352
+  flags:           0x00002000
+  reserved:        0x00000000
+LoadCommands:    
+  - cmd:             LC_SEGMENT_64
+    cmdsize:         232
+    segname:         ''
+    vmaddr:          0
+    vmsize:          56
+    fileoff:         384
+    filesize:        56
+    maxprot:         7
+    initprot:        7
+    nsects:          2
+    flags:           0
+    Sections:        
+      - sectname:        __text
+        segname:         __TEXT
+        addr:            0x0000000000000000
+        size:            20
+        offset:          0x00000180
+        align:           2
+        reloff:          0x00000000
+        nreloc:          0
+        flags:           0x80000400
+        reserved1:       0x00000000
+        reserved2:       0x00000000
+        reserved3:       0x00000000
+      - sectname:        __compact_unwind
+        segname:         __LD
+        addr:            0x0000000000000018
+        size:            32
+        offset:          0x00000198
+        align:           3
+        reloff:          0x000001B8
+        nreloc:          1
+        flags:           0x02000000
+        reserved1:       0x00000000
+        reserved2:       0x00000000
+        reserved3:       0x00000000
+  - cmd:             LC_VERSION_MIN_IPHONEOS
+    cmdsize:         16
+    version:         327680
+    sdk:             0
+  - cmd:             LC_SYMTAB
+    cmdsize:         24
+    symoff:          448
+    nsyms:           3
+    stroff:          496
+    strsize:         20
+  - cmd:             LC_DYSYMTAB
+    cmdsize:         80
+    ilocalsym:       0
+    nlocalsym:       2
+    iextdefsym:      2
+    nextdefsym:      1
+    iundefsym:       3
+    nundefsym:       0
+    tocoff:          0
+    ntoc:            0
+    modtaboff:       0
+    nmodtab:         0
+    extrefsymoff:    0
+    nextrefsyms:     0
+    indirectsymoff:  0
+    nindirectsyms:   0
+    extreloff:       0
+    nextrel:         0
+    locreloff:       0
+    nlocrel:         0
+LinkEditData:    
+  NameList:        
+    - n_strx:          13
+      n_type:          0x0E
+      n_sect:          1
+      n_desc:          0
+      n_value:         0
+    - n_strx:          7
+      n_type:          0x0E
+      n_sect:          2
+      n_desc:          0
+      n_value:         24
+    - n_strx:          1
+      n_type:          0x0F
+      n_sect:          1
+      n_desc:          0
+      n_value:         0
+  StringTable:     
+    - ''
+    - _main
+    - ltmp1
+    - ltmp0
+    - ''
+...
diff --git a/llvm/test/tools/llvm-lipo/Inputs/armv7-slice.yaml b/llvm/test/tools/llvm-lipo/Inputs/armv7-slice.yaml
new file mode 100644
index 00000000000..b2606293145
--- /dev/null
+++ b/llvm/test/tools/llvm-lipo/Inputs/armv7-slice.yaml
@@ -0,0 +1,76 @@
+--- !mach-o
+FileHeader:      
+  magic:           0xFEEDFACE
+  cputype:         0x0000000C
+  cpusubtype:      0x00000009
+  filetype:        0x00000001
+  ncmds:           4
+  sizeofcmds:      244
+  flags:           0x00002000
+LoadCommands:    
+  - cmd:             LC_SEGMENT
+    cmdsize:         124
+    segname:         ''
+    vmaddr:          0
+    vmsize:          10
+    fileoff:         272
+    filesize:        10
+    maxprot:         7
+    initprot:        7
+    nsects:          1
+    flags:           0
+    Sections:        
+      - sectname:        __text
+        segname:         __TEXT
+        addr:            0x0000000000000000
+        size:            10
+        offset:          0x00000110
+        align:           1
+        reloff:          0x00000000
+        nreloc:          0
+        flags:           0x80000400
+        reserved1:       0x00000000
+        reserved2:       0x00000000
+        reserved3:       0x00000000
+  - cmd:             LC_VERSION_MIN_IPHONEOS
+    cmdsize:         16
+    version:         327680
+    sdk:             0
+  - cmd:             LC_SYMTAB
+    cmdsize:         24
+    symoff:          284
+    nsyms:           1
+    stroff:          296
+    strsize:         8
+  - cmd:             LC_DYSYMTAB
+    cmdsize:         80
+    ilocalsym:       0
+    nlocalsym:       0
+    iextdefsym:      0
+    nextdefsym:      1
+    iundefsym:       1
+    nundefsym:       0
+    tocoff:          0
+    ntoc:            0
+    modtaboff:       0
+    nmodtab:         0
+    extrefsymoff:    0
+    nextrefsyms:     0
+    indirectsymoff:  0
+    nindirectsyms:   0
+    extreloff:       0
+    nextrel:         0
+    locreloff:       0
+    nlocrel:         0
+LinkEditData:    
+  NameList:        
+    - n_strx:          1
+      n_type:          0x0F
+      n_sect:          1
+      n_desc:          8
+      n_value:         0
+  StringTable:     
+    - ''
+    - _main
+    - ''
+...
diff --git a/llvm/test/tools/llvm-lipo/Inputs/x86_64-slice.yaml b/llvm/test/tools/llvm-lipo/Inputs/x86_64-slice.yaml
new file mode 100644
index 00000000000..27db6d7a131
--- /dev/null
+++ b/llvm/test/tools/llvm-lipo/Inputs/x86_64-slice.yaml
@@ -0,0 +1,89 @@
+--- !mach-o
+FileHeader:      
+  magic:           0xFEEDFACF
+  cputype:         0x01000007
+  cpusubtype:      0x00000003
+  filetype:        0x00000001
+  ncmds:           4
+  sizeofcmds:      352
+  flags:           0x00002000
+  reserved:        0x00000000
+LoadCommands:    
+  - cmd:             LC_SEGMENT_64
+    cmdsize:         232
+    segname:         ''
+    vmaddr:          0
+    vmsize:          80
+    fileoff:         384
+    filesize:        80
+    maxprot:         7
+    initprot:        7
+    nsects:          2
+    flags:           0
+    Sections:        
+      - sectname:        __text
+        segname:         __TEXT
+        addr:            0x0000000000000000
+        size:            15
+        offset:          0x00000180
+        align:           4
+        reloff:          0x00000000
+        nreloc:          0
+        flags:           0x80000400
+        reserved1:       0x00000000
+        reserved2:       0x00000000
+        reserved3:       0x00000000
+      - sectname:        __eh_frame
+        segname:         __TEXT
+        addr:            0x0000000000000010
+        size:            64
+        offset:          0x00000190
+        align:           3
+        reloff:          0x00000000
+        nreloc:          0
+        flags:           0x6800000B
+        reserved1:       0x00000000
+        reserved2:       0x00000000
+        reserved3:       0x00000000
+  - cmd:             LC_VERSION_MIN_MACOSX
+    cmdsize:         16
+    version:         656384
+    sdk:             0
+  - cmd:             LC_SYMTAB
+    cmdsize:         24
+    symoff:          464
+    nsyms:           1
+    stroff:          480
+    strsize:         8
+  - cmd:             LC_DYSYMTAB
+    cmdsize:         80
+    ilocalsym:       0
+    nlocalsym:       0
+    iextdefsym:      0
+    nextdefsym:      1
+    iundefsym:       1
+    nundefsym:       0
+    tocoff:          0
+    ntoc:            0
+    modtaboff:       0
+    nmodtab:         0
+    extrefsymoff:    0
+    nextrefsyms:     0
+    indirectsymoff:  0
+    nindirectsyms:   0
+    extreloff:       0
+    nextrel:         0
+    locreloff:       0
+    nlocrel:         0
+LinkEditData:    
+  NameList:        
+    - n_strx:          1
+      n_type:          0x0F
+      n_sect:          1
+      n_desc:          0
+      n_value:         0
+  StringTable:     
+    - ''
+    - _main
+    - ''
+...
diff --git a/llvm/test/tools/llvm-lipo/create-executable.test b/llvm/test/tools/llvm-lipo/create-executable.test
new file mode 100644
index 00000000000..19b3bfef3d4
--- /dev/null
+++ b/llvm/test/tools/llvm-lipo/create-executable.test
@@ -0,0 +1,13 @@
+# Executable testing is not supported on Windows, since all files are considered executable
+# UNSUPPORTED: system-windows
+# RUN: yaml2obj %p/Inputs/i386-slice.yaml > %t-i386.o
+# RUN: yaml2obj %p/Inputs/x86_64-slice.yaml > %t-x86_64.o
+
+# RUN: chmod -x %t-i386.o
+# RUN: chmod -x %t-x86_64.o
+# RUN: llvm-lipo %t-i386.o %t-x86_64.o -create -output %t-universal.o
+# RUN: test ! -x %t-universal.o
+
+# RUN: chmod +x %t-i386.o
+# RUN: llvm-lipo %t-i386.o %t-x86_64.o -create -output %t-universal.o
+# RUN: test -x %t-universal.o
diff --git a/llvm/test/tools/llvm-lipo/create-invalid-input.test b/llvm/test/tools/llvm-lipo/create-invalid-input.test
new file mode 100644
index 00000000000..4bb2e1a5666
--- /dev/null
+++ b/llvm/test/tools/llvm-lipo/create-invalid-input.test
@@ -0,0 +1,8 @@
+# RUN: yaml2obj %p/Inputs/i386-slice.yaml > %t-32.o
+# RUN: yaml2obj %p/Inputs/i386-x86_64-universal.yaml > %t-universal.o
+
+# RUN: not llvm-lipo %t-32.o -create 2>&1 | FileCheck --check-prefix=NO_OUTPUT %s
+# NO_OUTPUT: error: create expects a single output file to be specified
+
+# RUN: not llvm-lipo %t-universal.o %t-32.o -create -output %t.o 2>&1 | FileCheck --check-prefix=DUPLICATE_ARCHS %s
+# DUPLICATE_ARCHS: have the same architecture i386 and therefore cannot be in the same universal binary
diff --git a/llvm/test/tools/llvm-lipo/create-without-alignment.test b/llvm/test/tools/llvm-lipo/create-without-alignment.test
new file mode 100644
index 00000000000..813230a7e3c
--- /dev/null
+++ b/llvm/test/tools/llvm-lipo/create-without-alignment.test
@@ -0,0 +1,32 @@
+# RUN: yaml2obj %p/Inputs/i386-slice.yaml > %t-i386.o
+# RUN: yaml2obj %p/Inputs/x86_64-slice.yaml > %t-x86_64.o
+
+# RUN: llvm-lipo %t-i386.o %t-x86_64.o -create -output %t-universal-llvm.o
+
+# RUN: yaml2obj %p/Inputs/i386-x86_64-universal.yaml > %t-universal.o
+# RUN: cmp %t-universal-llvm.o %t-universal.o
+
+# RUN: yaml2obj %p/Inputs/armv7-slice.yaml > %t-armv7.o
+# RUN: yaml2obj %p/Inputs/arm64-slice.yaml > %t-arm64.o
+
+# RUN: llvm-lipo %t-arm64.o %t-armv7.o %t-universal.o -create -output %t-universal-2.o
+# RUN: llvm-lipo %t-universal-2.o -thin x86_64 -output %t-x86_64_extracted.o
+# RUN: cmp %t-x86_64_extracted.o %t-x86_64.o
+# RUN: llvm-lipo %t-universal-2.o -thin armv7 -output %t-armv7-extracted.o
+# RUN: cmp %t-armv7-extracted.o %t-armv7.o
+
+# RUN: llvm-objdump %t-universal-2.o -m --universal-headers | FileCheck %s
+# CHECK: fat_magic FAT_MAGIC
+# CHECK: nfat_arch 4
+# CHECK: architecture i386
+# CHECK: offset 4096
+# CHECK: align 2^12 (4096)
+# CHECK: architecture x86_64
+# CHECK: offset 8192
+# CHECK: align 2^12 (4096)
+# CHECK: architecture armv7
+# CHECK: offset 16384
+# CHECK: align 2^14 (16384)
+# CHECK: architecture arm64
+# CHECK: offset 32768
+# CHECK: align 2^14 (16384)
diff --git a/llvm/tools/llvm-lipo/LipoOpts.td b/llvm/tools/llvm-lipo/LipoOpts.td
index e3cbe2dfa8e..e2a73768733 100644
--- a/llvm/tools/llvm-lipo/LipoOpts.td
+++ b/llvm/tools/llvm-lipo/LipoOpts.td
@@ -23,6 +23,11 @@ def thin : Option<["-", "--"], "thin", KIND_SEPARATE>,
            HelpText<"Create a thin output file of specified arch_type from the "
                     "fat input file. Requires -output option">;
 
+def create : Option<["-", "--"], "create", KIND_FLAG>,
+             Group<action_group>,
+             HelpText<"Create a universal binary output file from the input "
+                      "files. Requires -output option">;
+
 def output : Option<["-", "--"], "output", KIND_SEPARATE>,
              HelpText<"Create output file with specified name">;
 def o : JoinedOrSeparate<["-"], "o">, Alias<output>;
diff --git a/llvm/tools/llvm-lipo/llvm-lipo.cpp b/llvm/tools/llvm-lipo/llvm-lipo.cpp
index ea0d427e019..65135bec951 100644
--- a/llvm/tools/llvm-lipo/llvm-lipo.cpp
+++ b/llvm/tools/llvm-lipo/llvm-lipo.cpp
@@ -80,6 +80,7 @@ enum class LipoAction {
   PrintArchs,
   VerifyArch,
   ThinArch,
+  CreateUniversal,
 };
 
 struct Config {
@@ -90,6 +91,14 @@ struct Config {
   LipoAction ActionToPerform;
 };
 
+struct Slice {
+  const MachOObjectFile *ObjectFile;
+  // Requires Alignment field to store slice alignment values from universal
+  // binaries. Also needed to order the slices using compareSlices, so the total
+  // file size can be calculated before creating the output buffer.
+  uint32_t Alignment;
+};
+
 } // end namespace
 
 static void validateArchitectureName(StringRef ArchitectureName) {
@@ -108,7 +117,7 @@ static Config parseLipoOptions(ArrayRef<const char *> ArgsArr) {
   Config C;
   LipoOptTable T;
   unsigned MissingArgumentIndex, MissingArgumentCount;
-  llvm::opt::InputArgList InputArgs =
+  opt::InputArgList InputArgs =
       T.ParseArgs(ArgsArr, MissingArgumentIndex, MissingArgumentCount);
 
   if (MissingArgumentCount)
@@ -186,6 +195,12 @@ static Config parseLipoOptions(ArrayRef<const char *> ArgsArr) {
     C.ActionToPerform = LipoAction::ThinArch;
     return C;
 
+  case LIPO_create:
+    if (C.OutputFile.empty())
+      reportError("create expects a single output file to be specified");
+    C.ActionToPerform = LipoAction::CreateUniversal;
+    return C;
+
   default:
     reportError("llvm-lipo action unspecified");
   }
@@ -195,8 +210,7 @@ static SmallVector<OwningBinary<Binary>, 1>
 readInputBinaries(ArrayRef<std::string> InputFiles) {
   SmallVector<OwningBinary<Binary>, 1> InputBinaries;
   for (StringRef InputFile : InputFiles) {
-    Expected<OwningBinary<llvm::object::Binary>> BinaryOrErr =
-        createBinary(InputFile);
+    Expected<OwningBinary<Binary>> BinaryOrErr = createBinary(InputFile);
     if (!BinaryOrErr)
       reportError(InputFile, BinaryOrErr.takeError());
     // TODO: Add compatibility for archive files
@@ -241,33 +255,35 @@ static void verifyArch(ArrayRef<OwningBinary<Binary>> InputBinaries,
   exit(EXIT_SUCCESS);
 }
 
-static void printArchOrUnknown(const MachOObjectFile *ObjectFile) {
-  // Prints trailing space and unknown in this format for compatibility with
-  // cctools lipo.
-  const std::string ObjectArch = ObjectFile->getArchTriple().getArchName();
-  if (ObjectArch.empty())
-    outs() << "unknown(" << ObjectFile->getHeader().cputype << ","
-           << ObjectFile->getHeader().cpusubtype << ") ";
-  else
-    outs() << ObjectArch + " ";
+// Returns a string of the given Object file's architecture type
+// Unknown architectures formatted unknown(CPUType,CPUSubType) for compatibility
+// with cctools lipo
+static std::string getArchString(const MachOObjectFile &ObjectFile) {
+  const Triple T = ObjectFile.getArchTriple();
+  const StringRef ObjectArch = T.getArchName();
+  if (!ObjectArch.empty())
+    return ObjectArch;
+  return ("unknown(" + Twine(ObjectFile.getHeader().cputype) + "," +
+          Twine(ObjectFile.getHeader().cpusubtype & ~MachO::CPU_SUBTYPE_MASK) +
+          ")")
+      .str();
 }
 
 LLVM_ATTRIBUTE_NORETURN
 static void printArchs(ArrayRef<OwningBinary<Binary>> InputBinaries) {
+  // Prints trailing space for compatibility with cctools lipo.
   assert(InputBinaries.size() == 1 && "Incorrect number of input binaries");
   const Binary *InputBinary = InputBinaries.front().getBinary();
   if (auto UO = dyn_cast<MachOUniversalBinary>(InputBinary)) {
-    for (MachOUniversalBinary::object_iterator I = UO->begin_objects(),
-                                               E = UO->end_objects();
-         I != E; ++I) {
+    for (const auto &O : UO->objects()) {
       Expected<std::unique_ptr<MachOObjectFile>> BinaryOrError =
-          I->getAsObjectFile();
+          O.getAsObjectFile();
       if (!BinaryOrError)
         reportError(InputBinary->getFileName(), BinaryOrError.takeError());
-      printArchOrUnknown(BinaryOrError.get().get());
+      outs() << getArchString(*BinaryOrError.get().get()) << " ";
     }
   } else if (auto O = dyn_cast<MachOObjectFile>(InputBinary)) {
-    printArchOrUnknown(O);
+    outs() << getArchString(*O) << " ";
   } else {
     llvm_unreachable("Unexpected binary format");
   }
@@ -314,6 +330,173 @@ static void extractSlice(ArrayRef<OwningBinary<Binary>> InputBinaries,
   exit(EXIT_SUCCESS);
 }
 
+static void checkArchDuplicates(const ArrayRef<Slice> &Slices) {
+  DenseMap<uint64_t, const MachOObjectFile *> CPUIds;
+  auto CPUIDForSlice = [](const Slice &S) {
+    return static_cast<uint64_t>(S.ObjectFile->getHeader().cputype) << 32 |
+           S.ObjectFile->getHeader().cpusubtype;
+  };
+  for (const auto &S : Slices) {
+    auto Entry = CPUIds.try_emplace(CPUIDForSlice(S), S.ObjectFile);
+    if (!Entry.second)
+      reportError(Entry.first->second->getFileName() + " and " +
+                  S.ObjectFile->getFileName() + " have the same architecture " +
+                  getArchString(*S.ObjectFile) +
+                  " and therefore cannot be in the same universal binary");
+  }
+}
+
+static uint32_t calculateAlignment(const MachOObjectFile *ObjectFile) {
+  // TODO: Implement getAlign() and remove hard coding
+  // Will be implemented in a follow-up.
+
+  switch (ObjectFile->getHeader().cputype) {
+  case MachO::CPU_TYPE_I386:
+  case MachO::CPU_TYPE_X86_64:
+  case MachO::CPU_TYPE_POWERPC:
+  case MachO::CPU_TYPE_POWERPC64:
+    return 12; // log2 value of page size(4k) for x86 and PPC
+  case MachO::CPU_TYPE_ARM:
+  case MachO::CPU_TYPE_ARM64:
+  case MachO::CPU_TYPE_ARM64_32:
+    return 14; // log2 value of page size(16k) for Darwin ARM
+  default:
+    return 12;
+  }
+}
+
+// This function replicates ordering from cctools lipo for consistency
+static bool compareSlices(const Slice &Lhs, const Slice &Rhs) {
+  if (Lhs.ObjectFile->getHeader().cputype ==
+      Rhs.ObjectFile->getHeader().cputype)
+    return Lhs.ObjectFile->getHeader().cpusubtype <
+           Rhs.ObjectFile->getHeader().cpusubtype;
+
+  // force arm64-family to follow after all other slices for compatibility
+  // with cctools lipo
+  if (Lhs.ObjectFile->getHeader().cputype == MachO::CPU_TYPE_ARM64)
+    return false;
+  if (Rhs.ObjectFile->getHeader().cputype == MachO::CPU_TYPE_ARM64)
+    return true;
+
+  // Sort by alignment to minimize file size
+  return Lhs.Alignment < Rhs.Alignment;
+}
+
+// Updates vector ExtractedObjects with the MachOObjectFiles extracted from
+// Universal Binary files to transfer ownership.
+static SmallVector<Slice, 2> buildSlices(
+    ArrayRef<OwningBinary<Binary>> InputBinaries,
+    SmallVectorImpl<std::unique_ptr<MachOObjectFile>> &ExtractedObjects) {
+  SmallVector<Slice, 2> Slices;
+  for (auto &IB : InputBinaries) {
+    const Binary *InputBinary = IB.getBinary();
+    if (auto UO = dyn_cast<MachOUniversalBinary>(InputBinary)) {
+      for (const auto &O : UO->objects()) {
+        Expected<std::unique_ptr<MachOObjectFile>> BinaryOrError =
+            O.getAsObjectFile();
+        if (!BinaryOrError)
+          reportError(InputBinary->getFileName(), BinaryOrError.takeError());
+        ExtractedObjects.push_back(std::move(BinaryOrError.get()));
+        Slices.push_back(Slice{ExtractedObjects.back().get(), O.getAlign()});
+      }
+    } else if (auto O = dyn_cast<MachOObjectFile>(InputBinary)) {
+      Slices.push_back(Slice{O, calculateAlignment(O)});
+    } else {
+      llvm_unreachable("Unexpected binary format");
+    }
+  }
+  return Slices;
+}
+
+static SmallVector<MachO::fat_arch, 2>
+buildFatArchList(ArrayRef<Slice> Slices) {
+  SmallVector<MachO::fat_arch, 2> FatArchList;
+  uint64_t Offset =
+      sizeof(MachO::fat_header) + Slices.size() * sizeof(MachO::fat_arch);
+
+  for (size_t Index = 0, Size = Slices.size(); Index < Size; ++Index) {
+    Offset = alignTo(Offset, 1 << Slices[Index].Alignment);
+    const MachOObjectFile *ObjectFile = Slices[Index].ObjectFile;
+    if (Offset > UINT32_MAX)
+      reportError("fat file too large to be created because the offset "
+                  "field in struct fat_arch is only 32-bits and the offset " +
+                  Twine(Offset) + " for " + ObjectFile->getFileName() +
+                  " for architecture " + getArchString(*ObjectFile) +
+                  "exceeds that.");
+
+    MachO::fat_arch FatArch;
+    FatArch.cputype = ObjectFile->getHeader().cputype;
+    FatArch.cpusubtype = ObjectFile->getHeader().cpusubtype;
+    FatArch.offset = Offset;
+    FatArch.size = ObjectFile->getMemoryBufferRef().getBufferSize();
+    FatArch.align = Slices[Index].Alignment;
+    Offset += FatArch.size;
+    FatArchList.push_back(FatArch);
+  }
+  return FatArchList;
+}
+
+static void createUniversalBinary(SmallVectorImpl<Slice> &Slices,
+                                  StringRef OutputFileName) {
+  MachO::fat_header FatHeader;
+  FatHeader.magic = MachO::FAT_MAGIC;
+  FatHeader.nfat_arch = Slices.size();
+
+  stable_sort(Slices, compareSlices);
+  SmallVector<MachO::fat_arch, 2> FatArchList = buildFatArchList(Slices);
+
+  const bool IsExecutable = any_of(Slices, [](Slice S) {
+    return sys::fs::can_execute(S.ObjectFile->getFileName());
+  });
+  const uint64_t OutputFileSize =
+      FatArchList.back().offset + FatArchList.back().size;
+  Expected<std::unique_ptr<FileOutputBuffer>> OutFileOrError =
+      FileOutputBuffer::create(OutputFileName, OutputFileSize,
+                               IsExecutable ? FileOutputBuffer::F_executable
+                                            : 0);
+  if (!OutFileOrError)
+    reportError(OutputFileName, OutFileOrError.takeError());
+  std::unique_ptr<FileOutputBuffer> OutFile = std::move(OutFileOrError.get());
+  std::memset(OutFile->getBufferStart(), 0, OutputFileSize);
+
+  if (sys::IsLittleEndianHost)
+    MachO::swapStruct(FatHeader);
+  std::memcpy(OutFile->getBufferStart(), &FatHeader, sizeof(MachO::fat_header));
+
+  for (size_t Index = 0, Size = Slices.size(); Index < Size; ++Index) {
+    MemoryBufferRef BufferRef = Slices[Index].ObjectFile->getMemoryBufferRef();
+    std::copy(BufferRef.getBufferStart(), BufferRef.getBufferEnd(),
+              OutFile->getBufferStart() + FatArchList[Index].offset);
+  }
+
+  // FatArchs written after Slices in order reduce the number of swaps for the
+  // LittleEndian case
+  if (sys::IsLittleEndianHost)
+    for (MachO::fat_arch &FA : FatArchList)
+      MachO::swapStruct(FA);
+  std::memcpy(OutFile->getBufferStart() + sizeof(MachO::fat_header),
+              FatArchList.begin(),
+              sizeof(MachO::fat_arch) * FatArchList.size());
+
+  if (Error E = OutFile->commit())
+    reportError(OutputFileName, std::move(E));
+}
+
+LLVM_ATTRIBUTE_NORETURN
+static void createUniversalBinary(ArrayRef<OwningBinary<Binary>> InputBinaries,
+                                  StringRef OutputFileName) {
+  assert(InputBinaries.size() >= 1 && "Incorrect number of input binaries");
+  assert(!OutputFileName.empty() && "Create expects a single output file");
+
+  SmallVector<std::unique_ptr<MachOObjectFile>, 1> ExtractedObjects;
+  SmallVector<Slice, 1> Slices = buildSlices(InputBinaries, ExtractedObjects);
+  checkArchDuplicates(Slices);
+  createUniversalBinary(Slices, OutputFileName);
+
+  exit(EXIT_SUCCESS);
+}
+
 int main(int argc, char **argv) {
   InitLLVM X(argc, argv);
   Config C = parseLipoOptions(makeArrayRef(argv + 1, argc));
@@ -330,6 +513,9 @@ int main(int argc, char **argv) {
   case LipoAction::ThinArch:
     extractSlice(InputBinaries, C.ThinArchType, C.OutputFile);
     break;
+  case LipoAction::CreateUniversal:
+    createUniversalBinary(InputBinaries, C.OutputFile);
+    break;
   }
   return EXIT_SUCCESS;
 }