diff --git a/src/arm64/instrument-arm64.cc b/src/arm64/instrument-arm64.cc
new file mode 100644
index 0000000..da505ff
--- /dev/null
+++ b/src/arm64/instrument-arm64.cc
@@ -0,0 +1,594 @@
+// Copyright 2013 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "src/arm64/instrument-arm64.h"
+
+namespace v8 {
+namespace internal {
+
+Counter::Counter(const char* name, CounterType type)
+    : count_(0), enabled_(false), type_(type) {
+  DCHECK(name != NULL);
+  strncpy(name_, name, kCounterNameMaxLength);
+}
+
+
+void Counter::Enable() {
+  enabled_ = true;
+}
+
+
+void Counter::Disable() {
+  enabled_ = false;
+}
+
+
+bool Counter::IsEnabled() {
+  return enabled_;
+}
+
+
+void Counter::Increment() {
+  if (enabled_) {
+    count_++;
+  }
+}
+
+
+uint64_t Counter::count() {
+  uint64_t result = count_;
+  if (type_ == Gauge) {
+    // If the counter is a Gauge, reset the count after reading.
+    count_ = 0;
+  }
+  return result;
+}
+
+
+const char* Counter::name() {
+  return name_;
+}
+
+
+CounterType Counter::type() {
+  return type_;
+}
+
+
+typedef struct {
+  const char* name;
+  CounterType type;
+} CounterDescriptor;
+
+
+static const CounterDescriptor kCounterList[] = {
+  {"Instruction", Cumulative},
+
+  {"Move Immediate", Gauge},
+  {"Add/Sub DP", Gauge},
+  {"Logical DP", Gauge},
+  {"Other Int DP", Gauge},
+  {"FP DP", Gauge},
+
+  {"Conditional Select", Gauge},
+  {"Conditional Compare", Gauge},
+
+  {"Unconditional Branch", Gauge},
+  {"Compare and Branch", Gauge},
+  {"Test and Branch", Gauge},
+  {"Conditional Branch", Gauge},
+
+  {"Load Integer", Gauge},
+  {"Load FP", Gauge},
+  {"Load Pair", Gauge},
+  {"Load Literal", Gauge},
+
+  {"Store Integer", Gauge},
+  {"Store FP", Gauge},
+  {"Store Pair", Gauge},
+
+  {"PC Addressing", Gauge},
+  {"Other", Gauge},
+  {"SP Adjust", Gauge},
+};
+
+
+Instrument::Instrument(const char* datafile, uint64_t sample_period)
+    : output_stream_(stderr), sample_period_(sample_period) {
+
+  // Set up the output stream. If datafile is non-NULL, use that file. If it
+  // can't be opened, or datafile is NULL, use stderr.
+  if (datafile != NULL) {
+    output_stream_ = fopen(datafile, "w");
+    if (output_stream_ == NULL) {
+      fprintf(stderr, "Can't open output file %s. Using stderr.\n", datafile);
+      output_stream_ = stderr;
+    }
+  }
+
+  static const int num_counters = arraysize(kCounterList);
+
+  // Dump an instrumentation description comment at the top of the file.
+  fprintf(output_stream_, "# counters=%d\n", num_counters);
+  fprintf(output_stream_, "# sample_period=%" PRIu64 "\n", sample_period_);
+
+  // Construct Counter objects from counter description array.
+  for (int i = 0; i < num_counters; i++) {
+    Counter* counter = new Counter(kCounterList[i].name, kCounterList[i].type);
+    counters_.push_back(counter);
+  }
+
+  DumpCounterNames();
+}
+
+
+Instrument::~Instrument() {
+  // Dump any remaining instruction data to the output file.
+  DumpCounters();
+
+  // Free all the counter objects.
+  std::list<Counter*>::iterator it;
+  for (it = counters_.begin(); it != counters_.end(); it++) {
+    delete *it;
+  }
+
+  if (output_stream_ != stderr) {
+    fclose(output_stream_);
+  }
+}
+
+
+void Instrument::Update() {
+  // Increment the instruction counter, and dump all counters if a sample period
+  // has elapsed.
+  static Counter* counter = GetCounter("Instruction");
+  DCHECK(counter->type() == Cumulative);
+  counter->Increment();
+
+  if (counter->IsEnabled() && (counter->count() % sample_period_) == 0) {
+    DumpCounters();
+  }
+}
+
+
+void Instrument::DumpCounters() {
+  // Iterate through the counter objects, dumping their values to the output
+  // stream.
+  std::list<Counter*>::const_iterator it;
+  for (it = counters_.begin(); it != counters_.end(); it++) {
+    fprintf(output_stream_, "%" PRIu64 ",", (*it)->count());
+  }
+  fprintf(output_stream_, "\n");
+  fflush(output_stream_);
+}
+
+
+void Instrument::DumpCounterNames() {
+  // Iterate through the counter objects, dumping the counter names to the
+  // output stream.
+  std::list<Counter*>::const_iterator it;
+  for (it = counters_.begin(); it != counters_.end(); it++) {
+    fprintf(output_stream_, "%s,", (*it)->name());
+  }
+  fprintf(output_stream_, "\n");
+  fflush(output_stream_);
+}
+
+
+void Instrument::HandleInstrumentationEvent(unsigned event) {
+  switch (event) {
+    case InstrumentStateEnable: Enable(); break;
+    case InstrumentStateDisable: Disable(); break;
+    default: DumpEventMarker(event);
+  }
+}
+
+
+void Instrument::DumpEventMarker(unsigned marker) {
+  // Dumpan event marker to the output stream as a specially formatted comment
+  // line.
+  static Counter* counter = GetCounter("Instruction");
+
+  fprintf(output_stream_, "# %c%c @ %" PRId64 "\n", marker & 0xff,
+          (marker >> 8) & 0xff, counter->count());
+}
+
+
+Counter* Instrument::GetCounter(const char* name) {
+  // Get a Counter object by name from the counter list.
+  std::list<Counter*>::const_iterator it;
+  for (it = counters_.begin(); it != counters_.end(); it++) {
+    if (strcmp((*it)->name(), name) == 0) {
+      return *it;
+    }
+  }
+
+  // A Counter by that name does not exist: print an error message to stderr
+  // and the output file, and exit.
+  static const char* error_message =
+    "# Error: Unknown counter \"%s\". Exiting.\n";
+  fprintf(stderr, error_message, name);
+  fprintf(output_stream_, error_message, name);
+  exit(1);
+}
+
+
+void Instrument::Enable() {
+  std::list<Counter*>::iterator it;
+  for (it = counters_.begin(); it != counters_.end(); it++) {
+    (*it)->Enable();
+  }
+}
+
+
+void Instrument::Disable() {
+  std::list<Counter*>::iterator it;
+  for (it = counters_.begin(); it != counters_.end(); it++) {
+    (*it)->Disable();
+  }
+}
+
+
+void Instrument::VisitPCRelAddressing(Instruction* instr) {
+  Update();
+  static Counter* counter = GetCounter("PC Addressing");
+  counter->Increment();
+}
+
+
+void Instrument::VisitAddSubImmediate(Instruction* instr) {
+  Update();
+  static Counter* sp_counter = GetCounter("SP Adjust");
+  static Counter* add_sub_counter = GetCounter("Add/Sub DP");
+  if (((instr->Mask(AddSubOpMask) == SUB) ||
+       (instr->Mask(AddSubOpMask) == ADD)) &&
+      (instr->Rd() == 31) && (instr->Rn() == 31)) {
+    // Count adjustments to the C stack pointer caused by V8 needing two SPs.
+    sp_counter->Increment();
+  } else {
+    add_sub_counter->Increment();
+  }
+}
+
+
+void Instrument::VisitLogicalImmediate(Instruction* instr) {
+  Update();
+  static Counter* counter = GetCounter("Logical DP");
+  counter->Increment();
+}
+
+
+void Instrument::VisitMoveWideImmediate(Instruction* instr) {
+  Update();
+  static Counter* counter = GetCounter("Move Immediate");
+
+  if (instr->IsMovn() && (instr->Rd() == kZeroRegCode)) {
+    unsigned imm = instr->ImmMoveWide();
+    HandleInstrumentationEvent(imm);
+  } else {
+    counter->Increment();
+  }
+}
+
+
+void Instrument::VisitBitfield(Instruction* instr) {
+  Update();
+  static Counter* counter = GetCounter("Other Int DP");
+  counter->Increment();
+}
+
+
+void Instrument::VisitExtract(Instruction* instr) {
+  Update();
+  static Counter* counter = GetCounter("Other Int DP");
+  counter->Increment();
+}
+
+
+void Instrument::VisitUnconditionalBranch(Instruction* instr) {
+  Update();
+  static Counter* counter = GetCounter("Unconditional Branch");
+  counter->Increment();
+}
+
+
+void Instrument::VisitUnconditionalBranchToRegister(Instruction* instr) {
+  Update();
+  static Counter* counter = GetCounter("Unconditional Branch");
+  counter->Increment();
+}
+
+
+void Instrument::VisitCompareBranch(Instruction* instr) {
+  Update();
+  static Counter* counter = GetCounter("Compare and Branch");
+  counter->Increment();
+}
+
+
+void Instrument::VisitTestBranch(Instruction* instr) {
+  Update();
+  static Counter* counter = GetCounter("Test and Branch");
+  counter->Increment();
+}
+
+
+void Instrument::VisitConditionalBranch(Instruction* instr) {
+  Update();
+  static Counter* counter = GetCounter("Conditional Branch");
+  counter->Increment();
+}
+
+
+void Instrument::VisitSystem(Instruction* instr) {
+  Update();
+  static Counter* counter = GetCounter("Other");
+  counter->Increment();
+}
+
+
+void Instrument::VisitException(Instruction* instr) {
+  Update();
+  static Counter* counter = GetCounter("Other");
+  counter->Increment();
+}
+
+
+void Instrument::InstrumentLoadStorePair(Instruction* instr) {
+  static Counter* load_pair_counter = GetCounter("Load Pair");
+  static Counter* store_pair_counter = GetCounter("Store Pair");
+  if (instr->Mask(LoadStorePairLBit) != 0) {
+    load_pair_counter->Increment();
+  } else {
+    store_pair_counter->Increment();
+  }
+}
+
+
+void Instrument::VisitLoadStorePairPostIndex(Instruction* instr) {
+  Update();
+  InstrumentLoadStorePair(instr);
+}
+
+
+void Instrument::VisitLoadStorePairOffset(Instruction* instr) {
+  Update();
+  InstrumentLoadStorePair(instr);
+}
+
+
+void Instrument::VisitLoadStorePairPreIndex(Instruction* instr) {
+  Update();
+  InstrumentLoadStorePair(instr);
+}
+
+
+void Instrument::VisitLoadStorePairNonTemporal(Instruction* instr) {
+  Update();
+  InstrumentLoadStorePair(instr);
+}
+
+
+void Instrument::VisitLoadLiteral(Instruction* instr) {
+  Update();
+  static Counter* counter = GetCounter("Load Literal");
+  counter->Increment();
+}
+
+
+void Instrument::InstrumentLoadStore(Instruction* instr) {
+  static Counter* load_int_counter = GetCounter("Load Integer");
+  static Counter* store_int_counter = GetCounter("Store Integer");
+  static Counter* load_fp_counter = GetCounter("Load FP");
+  static Counter* store_fp_counter = GetCounter("Store FP");
+
+  switch (instr->Mask(LoadStoreOpMask)) {
+    case STRB_w:    // Fall through.
+    case STRH_w:    // Fall through.
+    case STR_w:     // Fall through.
+    case STR_x:     store_int_counter->Increment(); break;
+    case STR_s:     // Fall through.
+    case STR_d:     store_fp_counter->Increment(); break;
+    case LDRB_w:    // Fall through.
+    case LDRH_w:    // Fall through.
+    case LDR_w:     // Fall through.
+    case LDR_x:     // Fall through.
+    case LDRSB_x:   // Fall through.
+    case LDRSH_x:   // Fall through.
+    case LDRSW_x:   // Fall through.
+    case LDRSB_w:   // Fall through.
+    case LDRSH_w:   load_int_counter->Increment(); break;
+    case LDR_s:     // Fall through.
+    case LDR_d:     load_fp_counter->Increment(); break;
+    default: UNREACHABLE();
+  }
+}
+
+
+void Instrument::VisitLoadStoreUnscaledOffset(Instruction* instr) {
+  Update();
+  InstrumentLoadStore(instr);
+}
+
+
+void Instrument::VisitLoadStorePostIndex(Instruction* instr) {
+  Update();
+  InstrumentLoadStore(instr);
+}
+
+
+void Instrument::VisitLoadStorePreIndex(Instruction* instr) {
+  Update();
+  InstrumentLoadStore(instr);
+}
+
+
+void Instrument::VisitLoadStoreRegisterOffset(Instruction* instr) {
+  Update();
+  InstrumentLoadStore(instr);
+}
+
+
+void Instrument::VisitLoadStoreUnsignedOffset(Instruction* instr) {
+  Update();
+  InstrumentLoadStore(instr);
+}
+
+
+void Instrument::VisitLogicalShifted(Instruction* instr) {
+  Update();
+  static Counter* counter = GetCounter("Logical DP");
+  counter->Increment();
+}
+
+
+void Instrument::VisitAddSubShifted(Instruction* instr) {
+  Update();
+  static Counter* counter = GetCounter("Add/Sub DP");
+  counter->Increment();
+}
+
+
+void Instrument::VisitAddSubExtended(Instruction* instr) {
+  Update();
+  static Counter* sp_counter = GetCounter("SP Adjust");
+  static Counter* add_sub_counter = GetCounter("Add/Sub DP");
+  if (((instr->Mask(AddSubOpMask) == SUB) ||
+       (instr->Mask(AddSubOpMask) == ADD)) &&
+      (instr->Rd() == 31) && (instr->Rn() == 31)) {
+    // Count adjustments to the C stack pointer caused by V8 needing two SPs.
+    sp_counter->Increment();
+  } else {
+    add_sub_counter->Increment();
+  }
+}
+
+
+void Instrument::VisitAddSubWithCarry(Instruction* instr) {
+  Update();
+  static Counter* counter = GetCounter("Add/Sub DP");
+  counter->Increment();
+}
+
+
+void Instrument::VisitConditionalCompareRegister(Instruction* instr) {
+  Update();
+  static Counter* counter = GetCounter("Conditional Compare");
+  counter->Increment();
+}
+
+
+void Instrument::VisitConditionalCompareImmediate(Instruction* instr) {
+  Update();
+  static Counter* counter = GetCounter("Conditional Compare");
+  counter->Increment();
+}
+
+
+void Instrument::VisitConditionalSelect(Instruction* instr) {
+  Update();
+  static Counter* counter = GetCounter("Conditional Select");
+  counter->Increment();
+}
+
+
+void Instrument::VisitDataProcessing1Source(Instruction* instr) {
+  Update();
+  static Counter* counter = GetCounter("Other Int DP");
+  counter->Increment();
+}
+
+
+void Instrument::VisitDataProcessing2Source(Instruction* instr) {
+  Update();
+  static Counter* counter = GetCounter("Other Int DP");
+  counter->Increment();
+}
+
+
+void Instrument::VisitDataProcessing3Source(Instruction* instr) {
+  Update();
+  static Counter* counter = GetCounter("Other Int DP");
+  counter->Increment();
+}
+
+
+void Instrument::VisitFPCompare(Instruction* instr) {
+  Update();
+  static Counter* counter = GetCounter("FP DP");
+  counter->Increment();
+}
+
+
+void Instrument::VisitFPConditionalCompare(Instruction* instr) {
+  Update();
+  static Counter* counter = GetCounter("Conditional Compare");
+  counter->Increment();
+}
+
+
+void Instrument::VisitFPConditionalSelect(Instruction* instr) {
+  Update();
+  static Counter* counter = GetCounter("Conditional Select");
+  counter->Increment();
+}
+
+
+void Instrument::VisitFPImmediate(Instruction* instr) {
+  Update();
+  static Counter* counter = GetCounter("FP DP");
+  counter->Increment();
+}
+
+
+void Instrument::VisitFPDataProcessing1Source(Instruction* instr) {
+  Update();
+  static Counter* counter = GetCounter("FP DP");
+  counter->Increment();
+}
+
+
+void Instrument::VisitFPDataProcessing2Source(Instruction* instr) {
+  Update();
+  static Counter* counter = GetCounter("FP DP");
+  counter->Increment();
+}
+
+
+void Instrument::VisitFPDataProcessing3Source(Instruction* instr) {
+  Update();
+  static Counter* counter = GetCounter("FP DP");
+  counter->Increment();
+}
+
+
+void Instrument::VisitFPIntegerConvert(Instruction* instr) {
+  Update();
+  static Counter* counter = GetCounter("FP DP");
+  counter->Increment();
+}
+
+
+void Instrument::VisitFPFixedPointConvert(Instruction* instr) {
+  Update();
+  static Counter* counter = GetCounter("FP DP");
+  counter->Increment();
+}
+
+
+void Instrument::VisitUnallocated(Instruction* instr) {
+  Update();
+  static Counter* counter = GetCounter("Other");
+  counter->Increment();
+}
+
+
+void Instrument::VisitUnimplemented(Instruction* instr) {
+  Update();
+  static Counter* counter = GetCounter("Other");
+  counter->Increment();
+}
+
+
+} }  // namespace v8::internal