diff --git a/llvm/lib/CodeGen/AsmPrinter/AccelTable.cpp b/llvm/lib/CodeGen/AsmPrinter/AccelTable.cpp
new file mode 100644
index 0000000..026573b
--- /dev/null
+++ b/llvm/lib/CodeGen/AsmPrinter/AccelTable.cpp
@@ -0,0 +1,221 @@
+//===- llvm/CodeGen/AsmPrinter/AccelTable.cpp - Accelerator Tables --------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains support for writing accelerator tables.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/AccelTable.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/StringMap.h"
+#include "llvm/ADT/Twine.h"
+#include "llvm/BinaryFormat/Dwarf.h"
+#include "llvm/CodeGen/AsmPrinter.h"
+#include "llvm/CodeGen/DIE.h"
+#include "llvm/MC/MCExpr.h"
+#include "llvm/MC/MCStreamer.h"
+#include "llvm/Support/raw_ostream.h"
+#include <algorithm>
+#include <cstddef>
+#include <cstdint>
+#include <limits>
+#include <vector>
+
+using namespace llvm;
+
+void AppleAccelTableHeader::emit(AsmPrinter *Asm) {
+  // Emit Header.
+  Asm->OutStreamer->AddComment("Header Magic");
+  Asm->EmitInt32(Header.Magic);
+  Asm->OutStreamer->AddComment("Header Version");
+  Asm->EmitInt16(Header.Version);
+  Asm->OutStreamer->AddComment("Header Hash Function");
+  Asm->EmitInt16(Header.HashFunction);
+  Asm->OutStreamer->AddComment("Header Bucket Count");
+  Asm->EmitInt32(Header.BucketCount);
+  Asm->OutStreamer->AddComment("Header Hash Count");
+  Asm->EmitInt32(Header.HashCount);
+  Asm->OutStreamer->AddComment("Header Data Length");
+  Asm->EmitInt32(Header.HeaderDataLength);
+
+  //  Emit Header Data
+  Asm->OutStreamer->AddComment("HeaderData Die Offset Base");
+  Asm->EmitInt32(HeaderData.DieOffsetBase);
+  Asm->OutStreamer->AddComment("HeaderData Atom Count");
+  Asm->EmitInt32(HeaderData.Atoms.size());
+
+  for (size_t i = 0; i < HeaderData.Atoms.size(); i++) {
+    Atom A = HeaderData.Atoms[i];
+    Asm->OutStreamer->AddComment(dwarf::AtomTypeString(A.Type));
+    Asm->EmitInt16(A.Type);
+    Asm->OutStreamer->AddComment(dwarf::FormEncodingString(A.Form));
+    Asm->EmitInt16(A.Form);
+  }
+}
+
+void AppleAccelTableHeader::setBucketAndHashCount(uint32_t HashCount) {
+  if (HashCount > 1024)
+    Header.BucketCount = HashCount / 4;
+  else if (HashCount > 16)
+    Header.BucketCount = HashCount / 2;
+  else
+    Header.BucketCount = HashCount > 0 ? HashCount : 1;
+
+  Header.HashCount = HashCount;
+}
+
+constexpr AppleAccelTableHeader::Atom AppleAccelTableTypeData::Atoms[];
+constexpr AppleAccelTableHeader::Atom AppleAccelTableOffsetData::Atoms[];
+
+void AppleAccelTableBase::emitHeader(AsmPrinter *Asm) { Header.emit(Asm); }
+
+void AppleAccelTableBase::emitBuckets(AsmPrinter *Asm) {
+  unsigned index = 0;
+  for (size_t i = 0, e = Buckets.size(); i < e; ++i) {
+    Asm->OutStreamer->AddComment("Bucket " + Twine(i));
+    if (!Buckets[i].empty())
+      Asm->EmitInt32(index);
+    else
+      Asm->EmitInt32(std::numeric_limits<uint32_t>::max());
+    // Buckets point in the list of hashes, not to the data. Do not increment
+    // the index multiple times in case of hash collisions.
+    uint64_t PrevHash = std::numeric_limits<uint64_t>::max();
+    for (auto *HD : Buckets[i]) {
+      uint32_t HashValue = HD->HashValue;
+      if (PrevHash != HashValue)
+        ++index;
+      PrevHash = HashValue;
+    }
+  }
+}
+
+void AppleAccelTableBase::emitHashes(AsmPrinter *Asm) {
+  uint64_t PrevHash = std::numeric_limits<uint64_t>::max();
+  unsigned BucketIdx = 0;
+  for (auto &Bucket : Buckets) {
+    for (auto &Hash : Bucket) {
+      uint32_t HashValue = Hash->HashValue;
+      if (PrevHash == HashValue)
+        continue;
+      Asm->OutStreamer->AddComment("Hash in Bucket " + Twine(BucketIdx));
+      Asm->EmitInt32(HashValue);
+      PrevHash = HashValue;
+    }
+    BucketIdx++;
+  }
+}
+
+void AppleAccelTableBase::emitOffsets(AsmPrinter *Asm,
+                                      const MCSymbol *SecBegin) {
+  uint64_t PrevHash = std::numeric_limits<uint64_t>::max();
+  for (size_t i = 0, e = Buckets.size(); i < e; ++i) {
+    for (auto HI = Buckets[i].begin(), HE = Buckets[i].end(); HI != HE; ++HI) {
+      uint32_t HashValue = (*HI)->HashValue;
+      if (PrevHash == HashValue)
+        continue;
+      PrevHash = HashValue;
+      Asm->OutStreamer->AddComment("Offset in Bucket " + Twine(i));
+      MCContext &Context = Asm->OutStreamer->getContext();
+      const MCExpr *Sub = MCBinaryExpr::createSub(
+          MCSymbolRefExpr::create((*HI)->Sym, Context),
+          MCSymbolRefExpr::create(SecBegin, Context), Context);
+      Asm->OutStreamer->EmitValue(Sub, sizeof(uint32_t));
+    }
+  }
+}
+
+void AppleAccelTableBase::emitData(AsmPrinter *Asm) {
+  for (size_t i = 0, e = Buckets.size(); i < e; ++i) {
+    uint64_t PrevHash = std::numeric_limits<uint64_t>::max();
+    for (auto &Hash : Buckets[i]) {
+      // Terminate the previous entry if there is no hash collision with the
+      // current one.
+      if (PrevHash != std::numeric_limits<uint64_t>::max() &&
+          PrevHash != Hash->HashValue)
+        Asm->EmitInt32(0);
+      // Remember to emit the label for our offset.
+      Asm->OutStreamer->EmitLabel(Hash->Sym);
+      Asm->OutStreamer->AddComment(Hash->Str);
+      Asm->emitDwarfStringOffset(Hash->Data.Name);
+      Asm->OutStreamer->AddComment("Num DIEs");
+      Asm->EmitInt32(Hash->Data.Values.size());
+      for (const auto *V : Hash->Data.Values) {
+        V->emit(Asm);
+      }
+      PrevHash = Hash->HashValue;
+    }
+    // Emit the final end marker for the bucket.
+    if (!Buckets[i].empty())
+      Asm->EmitInt32(0);
+  }
+}
+
+void AppleAccelTableBase::computeBucketCount() {
+  // First get the number of unique hashes.
+  std::vector<uint32_t> uniques(Data.size());
+  for (size_t i = 0, e = Data.size(); i < e; ++i)
+    uniques[i] = Data[i]->HashValue;
+  array_pod_sort(uniques.begin(), uniques.end());
+  std::vector<uint32_t>::iterator p =
+      std::unique(uniques.begin(), uniques.end());
+
+  // Compute the hashes count and use it to set that together with the bucket
+  // count in the header.
+  Header.setBucketAndHashCount(std::distance(uniques.begin(), p));
+}
+
+void AppleAccelTableBase::finalizeTable(AsmPrinter *Asm, StringRef Prefix) {
+  // Create the individual hash data outputs.
+  Data.reserve(Entries.size());
+  for (auto &E : Entries) {
+    // Unique the entries.
+    std::stable_sort(E.second.Values.begin(), E.second.Values.end(),
+                     [](const AppleAccelTableData *A,
+                        const AppleAccelTableData *B) { return *A < *B; });
+    E.second.Values.erase(
+        std::unique(E.second.Values.begin(), E.second.Values.end()),
+        E.second.Values.end());
+
+    HashData *Entry = new (Allocator) HashData(E.first(), E.second);
+    Data.push_back(Entry);
+  }
+
+  // Figure out how many buckets we need, then compute the bucket contents and
+  // the final ordering. We'll emit the hashes and offsets by doing a walk
+  // during the emission phase. We add temporary symbols to the data so that we
+  // can reference them during the offset later, we'll emit them when we emit
+  // the data.
+  computeBucketCount();
+
+  // Compute bucket contents and final ordering.
+  Buckets.resize(Header.getBucketCount());
+  for (auto &D : Data) {
+    uint32_t bucket = D->HashValue % Header.getBucketCount();
+    Buckets[bucket].push_back(D);
+    D->Sym = Asm->createTempSymbol(Prefix);
+  }
+
+  // Sort the contents of the buckets by hash value so that hash collisions end
+  // up together. Stable sort makes testing easier and doesn't cost much more.
+  for (auto &Bucket : Buckets)
+    std::stable_sort(Bucket.begin(), Bucket.end(),
+                     [](HashData *LHS, HashData *RHS) {
+                       return LHS->HashValue < RHS->HashValue;
+                     });
+}
+
+void AppleAccelTableOffsetData::emit(AsmPrinter *Asm) const {
+  Asm->EmitInt32(Die->getDebugSectionOffset());
+}
+
+void AppleAccelTableTypeData::emit(AsmPrinter *Asm) const {
+  Asm->EmitInt32(Die->getDebugSectionOffset());
+  Asm->EmitInt16(Die->getTag());
+  Asm->EmitInt8(0);
+}