diff --git a/llvm/lib/ObjCopy/XCOFF/XCOFFReader.cpp b/llvm/lib/ObjCopy/XCOFF/XCOFFReader.cpp
@@ -0,0 +1,101 @@
+//===- XCOFFReader.cpp ----------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "XCOFFReader.h"
+
+namespace llvm {
+namespace objcopy {
+namespace xcoff {
+
+using namespace object;
+
+Error XCOFFReader::readSections(Object &Obj) const {
+  ArrayRef<XCOFFSectionHeader32> Sections = XCOFFObj.sections32();
+  for (const XCOFFSectionHeader32 &Sec : Sections) {
+    Section ReadSec;
+    // Section header.
+    ReadSec.SectionHeader = Sec;
+    DataRefImpl SectionDRI;
+    SectionDRI.p = reinterpret_cast<uintptr_t>(&Sec);
+
+    // Section data.
+    if (Sec.SectionSize) {
+      Expected<ArrayRef<uint8_t>> ContentsRef =
+          XCOFFObj.getSectionContents(SectionDRI);
+      if (!ContentsRef)
+        return ContentsRef.takeError();
+      ReadSec.Contents = ContentsRef.get();
+    }
+
+    // Relocations.
+    if (Sec.NumberOfRelocations) {
+      auto Relocations =
+          XCOFFObj.relocations<XCOFFSectionHeader32, XCOFFRelocation32>(Sec);
+      if (!Relocations)
+        return Relocations.takeError();
+      for (const XCOFFRelocation32 &Rel : Relocations.get())
+        ReadSec.Relocations.push_back(Rel);
+    }
+
+    Obj.Sections.push_back(std::move(ReadSec));
+  }
+  return Error::success();
+}
+
+Error XCOFFReader::readSymbols(Object &Obj) const {
+  std::vector<Symbol> Symbols;
+  Symbols.reserve(XCOFFObj.getNumberOfSymbolTableEntries());
+  for (SymbolRef Sym : XCOFFObj.symbols()) {
+    Symbol ReadSym;
+    DataRefImpl SymbolDRI = Sym.getRawDataRefImpl();
+    XCOFFSymbolRef SymbolEntRef = XCOFFObj.toSymbolRef(SymbolDRI);
+    ReadSym.Sym = *SymbolEntRef.getSymbol32();
+    // Auxiliary entries.
+    if (SymbolEntRef.getNumberOfAuxEntries()) {
+      const char *Start = reinterpret_cast<const char *>(
+          SymbolDRI.p + XCOFF::SymbolTableEntrySize);
+      Expected<StringRef> RawAuxEntriesOrError = XCOFFObj.getRawData(
+          Start,
+          XCOFF::SymbolTableEntrySize * SymbolEntRef.getNumberOfAuxEntries(),
+          StringRef("symbol"));
+      if (!RawAuxEntriesOrError)
+        return RawAuxEntriesOrError.takeError();
+      ReadSym.AuxSymbolEntries = RawAuxEntriesOrError.get();
+    }
+    Obj.Symbols.push_back(std::move(ReadSym));
+  }
+  return Error::success();
+}
+
+Expected<std::unique_ptr<Object>> XCOFFReader::create() const {
+  auto Obj = std::make_unique<Object>();
+  // Only 32-bit supported now.
+  if (XCOFFObj.is64Bit())
+    return createStringError(object_error::invalid_file_type,
+                             "64-bit XCOFF is not supported yet");
+  // Read the file header.
+  Obj->FileHeader = *XCOFFObj.fileHeader32();
+  // Read the optional header.
+  if (XCOFFObj.getOptionalHeaderSize())
+    Obj->OptionalFileHeader = *XCOFFObj.auxiliaryHeader32();
+  // Read each section.
+  Obj->Sections.reserve(XCOFFObj.getNumberOfSections());
+  if (Error E = readSections(*Obj))
+    return std::move(E);
+  // Read each symbol.
+  Obj->Symbols.reserve(XCOFFObj.getRawNumberOfSymbolTableEntries32());
+  if (Error E = readSymbols(*Obj))
+    return std::move(E);
+  // String table.
+  Obj->StringTable = XCOFFObj.getStringTable();
+  return std::move(Obj);
+}
+
+} // end namespace xcoff
+} // end namespace objcopy
+} // end namespace llvm
diff --git a/llvm/lib/ObjCopy/XCOFF/XCOFFReader.h b/llvm/lib/ObjCopy/XCOFF/XCOFFReader.h
@@ -0,0 +1,35 @@
+//===- XCOFFReader.h --------------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIB_OBJCOPY_XCOFF_XCOFFREADER_H
+#define LLVM_LIB_OBJCOPY_XCOFF_XCOFFREADER_H
+
+#include "XCOFFObject.h"
+
+namespace llvm {
+namespace objcopy {
+namespace xcoff {
+
+using namespace object;
+
+class XCOFFReader {
+public:
+  explicit XCOFFReader(const XCOFFObjectFile &O) : XCOFFObj(O) {}
+  Expected<std::unique_ptr<Object>> create() const;
+
+private:
+  const XCOFFObjectFile &XCOFFObj;
+  Error readSections(Object &Obj) const;
+  Error readSymbols(Object &Obj) const;
+};
+
+} // end namespace xcoff
+} // end namespace objcopy
+} // end namespace llvm
+
+#endif // LLVM_LIB_OBJCOPY_XCOFF_XCOFFREADER_H
diff --git a/llvm/lib/ObjCopy/XCOFF/XCOFFWriter.cpp b/llvm/lib/ObjCopy/XCOFF/XCOFFWriter.cpp
@@ -0,0 +1,125 @@
+//===- XCOFFWriter.cpp ----------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/Errc.h"
+#include "XCOFFWriter.h"
+
+namespace llvm {
+namespace objcopy {
+namespace xcoff {
+
+using namespace object;
+
+void XCOFFWriter::finalizeHeaders() {
+  // File header.
+  FileSize += sizeof(XCOFFFileHeader32);
+  // Optional file header.
+  FileSize += Obj.FileHeader.AuxHeaderSize;
+  // Section headers.
+  FileSize += sizeof(XCOFFSectionHeader32) * Obj.Sections.size();
+}
+
+void XCOFFWriter::finalizeSections() {
+  for (const Section &Sec : Obj.Sections) {
+    // Section data.
+    FileSize += Sec.Contents.size();
+    // Relocations.
+    FileSize +=
+        Sec.SectionHeader.NumberOfRelocations * sizeof(XCOFFRelocation32);
+  }
+}
+
+void XCOFFWriter::finalizeSymbolStringTable() {
+  assert(Obj.FileHeader.SymbolTableOffset >= FileSize);
+  FileSize = Obj.FileHeader.SymbolTableOffset;
+  // Symbols and auxiliary entries.
+  FileSize +=
+      Obj.FileHeader.NumberOfSymTableEntries * XCOFF::SymbolTableEntrySize;
+  // String table.
+  FileSize += Obj.StringTable.size();
+}
+
+void XCOFFWriter::finalize() {
+  FileSize = 0;
+  finalizeHeaders();
+  finalizeSections();
+  finalizeSymbolStringTable();
+}
+
+void XCOFFWriter::writeHeaders() {
+  // Write the file header.
+  uint8_t *Ptr = reinterpret_cast<uint8_t *>(Buf->getBufferStart());
+  memcpy(Ptr, &Obj.FileHeader, sizeof(XCOFFFileHeader32));
+  Ptr += sizeof(XCOFFFileHeader32);
+
+  // Write the optional header.
+  if (Obj.FileHeader.AuxHeaderSize) {
+    memcpy(Ptr, &Obj.OptionalFileHeader, Obj.FileHeader.AuxHeaderSize);
+    Ptr += Obj.FileHeader.AuxHeaderSize;
+  }
+
+  // Write section headers.
+  for (const Section &Sec : Obj.Sections) {
+    memcpy(Ptr, &Sec.SectionHeader, sizeof(XCOFFSectionHeader32));
+    Ptr += sizeof(XCOFFSectionHeader32);
+  }
+}
+
+void XCOFFWriter::writeSections() {
+  // Write section data.
+  for (const Section &Sec : Obj.Sections) {
+    uint8_t *Ptr = reinterpret_cast<uint8_t *>(Buf->getBufferStart()) +
+                   Sec.SectionHeader.FileOffsetToRawData;
+    Ptr = std::copy(Sec.Contents.begin(), Sec.Contents.end(), Ptr);
+  }
+
+  // Write relocations.
+  for (const Section &Sec : Obj.Sections) {
+    uint8_t *Ptr = reinterpret_cast<uint8_t *>(Buf->getBufferStart()) +
+                   Sec.SectionHeader.FileOffsetToRelocationInfo;
+    for (const XCOFFRelocation32 &Rel : Sec.Relocations) {
+      memcpy(Ptr, &Rel, sizeof(XCOFFRelocation32));
+      Ptr += sizeof(XCOFFRelocation32);
+    }
+  }
+}
+
+void XCOFFWriter::writeSymbolStringTable() {
+  // Write symbols.
+  uint8_t *Ptr = reinterpret_cast<uint8_t *>(Buf->getBufferStart()) +
+                 Obj.FileHeader.SymbolTableOffset;
+  for (const Symbol &Sym : Obj.Symbols) {
+    memcpy(Ptr, &Sym.Sym, XCOFF::SymbolTableEntrySize);
+    Ptr += XCOFF::SymbolTableEntrySize;
+    // Auxiliary symbols.
+    memcpy(Ptr, Sym.AuxSymbolEntries.data(), Sym.AuxSymbolEntries.size());
+    Ptr += Sym.AuxSymbolEntries.size();
+  }
+  // Write the string table.
+  memcpy(Ptr, Obj.StringTable.data(), Obj.StringTable.size());
+  Ptr += Obj.StringTable.size();
+}
+
+Error XCOFFWriter::write() {
+  finalize();
+  Buf = WritableMemoryBuffer::getNewMemBuffer(FileSize);
+  if (!Buf)
+    return createStringError(errc::not_enough_memory,
+                             "failed to allocate memory buffer of " +
+                                 Twine::utohexstr(FileSize) + " bytes");
+
+  writeHeaders();
+  writeSections();
+  writeSymbolStringTable();
+  Out.write(Buf->getBufferStart(), Buf->getBufferSize());
+  return Error::success();
+}
+
+} // end namespace xcoff
+} // end namespace objcopy
+} // end namespace llvm
diff --git a/llvm/lib/ObjCopy/XCOFF/XCOFFWriter.h b/llvm/lib/ObjCopy/XCOFF/XCOFFWriter.h
@@ -0,0 +1,48 @@
+//===- XCOFFWriter.h --------------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIB_OBJCOPY_XCOFF_XCOFFWRITER_H
+#define LLVM_LIB_OBJCOPY_XCOFF_XCOFFWRITER_H
+
+#include "llvm/Support/MemoryBuffer.h"
+#include "XCOFFObject.h"
+
+#include <cstdint>
+#include <vector>
+
+namespace llvm {
+namespace objcopy {
+namespace xcoff {
+
+class XCOFFWriter {
+public:
+  virtual ~XCOFFWriter() {}
+  XCOFFWriter(Object &Obj, raw_ostream &Out) : Obj(Obj), Out(Out) {}
+  Error write();
+
+private:
+  Object &Obj;
+  raw_ostream &Out;
+  std::unique_ptr<WritableMemoryBuffer> Buf;
+  size_t FileSize;
+
+  void finalizeHeaders();
+  void finalizeSections();
+  void finalizeSymbolStringTable();
+  void finalize();
+
+  void writeHeaders();
+  void writeSections();
+  void writeSymbolStringTable();
+};
+
+} // end namespace xcoff
+} // end namespace objcopy
+} // end namespace llvm
+
+#endif // LLVM_LIB_OBJCOPY_XCOFF_XCOFFWRITER_H
diff --git a/llvm/lib/Object/XCOFFObjectFile.cpp b/llvm/lib/Object/XCOFFObjectFile.cpp
@@ -709,6 +709,19 @@ bool XCOFFObjectFile::is64Bit() const {
   return Binary::ID_XCOFF64 == getType();
 }
 
+Expected<StringRef> XCOFFObjectFile::getRawData(const char *Start,
+                                                uint64_t Size,
+                                                StringRef Name) const {
+  uintptr_t StartPtr = reinterpret_cast<uintptr_t>(Start);
+  // TODO: this path is untested.
+  if (Error E = Binary::checkOffset(Data, StartPtr, Size))
+    return createError(toString(std::move(E)) + ": " + Name.data() +
+                       " data with offset 0x" + Twine::utohexstr(StartPtr) +
+                       " and size 0x" + Twine::utohexstr(Size) +
+                       " goes past the end of the file");
+  return StringRef(Start, Size);
+}
+
 uint16_t XCOFFObjectFile::getMagic() const {
   return is64Bit() ? fileHeader64()->Magic : fileHeader32()->Magic;
 }

diff --git a/llvm/test/tools/llvm-objcopy/XCOFF/basic-copy.test b/llvm/test/tools/llvm-objcopy/XCOFF/basic-copy.test
@@ -0,0 +1,31 @@
+# RUN: yaml2obj %s -o %t
+# RUN: llvm-objcopy %t %t.out
+# RUN: cmp %t %t.out
+
+--- !XCOFF
+FileHeader:
+  MagicNumber: 0x1DF
+AuxiliaryHeader:
+  Magic: 0x10B
+Sections:
+  - Name:        .text
+    Flags:       [ STYP_TEXT ]
+    SectionData: "123456"
+  - Name:        .data
+    Flags:       [ STYP_DATA ]
+    SectionData: "067891"
+    Relocations:
+      - Address: 0x3A
+        Type:    0x02
+Symbols:
+  - Name:         aux_fcn_csect
+    StorageClass: C_EXT
+    Type:         0x20
+    AuxEntries:
+      - Type: AUX_FCN
+      - Type: AUX_CSECT
+  - Name:         aux_stat
+    StorageClass: C_STAT
+    AuxEntries:
+      - Type: AUX_STAT
+...
diff --git a/llvm/test/tools/llvm-objcopy/XCOFF/invalid-read.test b/llvm/test/tools/llvm-objcopy/XCOFF/invalid-read.test
@@ -0,0 +1,47 @@
+## Check that llvm-objcopy reports a suitable error when it
+## encounters invalid input during reading.
+
+## Failed to read section data.
+# RUN: yaml2obj %s --docnum=1 -o %t1
+# RUN: not llvm-objcopy %t1 %t1.out 2>&1 | FileCheck %s -DFILE=%t1 --check-prefix=ERROR1
+
+# ERROR1: error: '[[FILE]]': The end of the file was unexpectedly encountered: section data with offset 0x70 and size 0x4 goes past the end of the file
+
+--- !XCOFF
+FileHeader:
+  MagicNumber: 0x01DF
+Sections:
+  - SectionData:      '00007400'
+    FileOffsetToData: 0x70
+
+## Failed to read relocations.
+# RUN: yaml2obj %s --docnum=2 -o %t2
+# RUN: not llvm-objcopy %t2 %t2.out 2>&1 | FileCheck %s -DFILE=%t2 --check-prefix=ERROR2
+
+# ERROR2: error: '[[FILE]]': The end of the file was unexpectedly encountered: relocations with offset 0x3c and size 0x1e go past the end of the file
+
+--- !XCOFF
+FileHeader:
+  MagicNumber: 0x01DF
+Sections:
+  - NumberOfRelocations: 0x3
+    Relocations:
+      - Address: 0xE
+        Symbol:  0x12
+        Info:    0xF
+        Type:    0x3
+
+## Failed to read the symbols.
+# RUN: yaml2obj %s --docnum=3 -o %t3
+# RUN: not llvm-objcopy %t3 %t3.out 2>&1 | FileCheck %s -DFILE=%t3 --check-prefix=ERROR3
+
+# ERROR3: error: '[[FILE]]': The end of the file was unexpectedly encountered: symbol table with offset 0x15 and size 0x24 goes past the end of the file
+
+--- !XCOFF
+FileHeader:
+  MagicNumber:         0x01DF
+  OffsetToSymbolTable: 0x15
+Symbols:
+  - Name:         foo
+    AuxEntries:
+      - Type: AUX_CSECT