diff --git a/libfdtrack/.clang-format b/libfdtrack/.clang-format
new file mode 120000
index 0000000..fd0645f
--- /dev/null
+++ b/libfdtrack/.clang-format
@@ -0,0 +1 @@
+../.clang-format-2
\ No newline at end of file
diff --git a/libfdtrack/Android.bp b/libfdtrack/Android.bp
new file mode 100644
index 0000000..fd13512
--- /dev/null
+++ b/libfdtrack/Android.bp
@@ -0,0 +1,18 @@
+cc_library_shared {
+    name: "libfdtrack",
+    srcs: ["fdtrack.cpp"],
+    stl: "libc++_static",
+
+    header_libs: ["bionic_libc_platform_headers"],
+    static_libs: [
+        "libasync_safe",
+        "libbase",
+        "libunwindstack",
+        "liblzma",
+        "liblog",
+    ],
+    version_script: "libfdtrack.map.txt",
+
+    allow_undefined_symbols: true,
+    recovery_available: true,
+}
diff --git a/libfdtrack/fdtrack.cpp b/libfdtrack/fdtrack.cpp
new file mode 100644
index 0000000..7c4cfbf
--- /dev/null
+++ b/libfdtrack/fdtrack.cpp
@@ -0,0 +1,127 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <inttypes.h>
+
+#include <array>
+#include <mutex>
+#include <vector>
+
+#include <android/fdtrack.h>
+
+#include <android-base/no_destructor.h>
+#include <android-base/thread_annotations.h>
+#include <async_safe/log.h>
+#include <bionic/reserved_signals.h>
+#include <unwindstack/LocalUnwinder.h>
+
+struct FdEntry {
+  std::mutex mutex;
+  std::vector<unwindstack::LocalFrameData> backtrace GUARDED_BY(mutex);
+};
+
+extern "C" void fdtrack_dump();
+static void fd_hook(android_fdtrack_event* event);
+
+// Backtraces for the first 4k file descriptors ought to be enough to diagnose an fd leak.
+static constexpr size_t kFdTableSize = 4096;
+static constexpr size_t kStackDepth = 10;
+
+static bool installed = false;
+static std::array<FdEntry, kFdTableSize> stack_traces;
+static unwindstack::LocalUnwinder& Unwinder() {
+  static android::base::NoDestructor<unwindstack::LocalUnwinder> unwinder;
+  return *unwinder.get();
+}
+
+__attribute__((constructor)) static void ctor() {
+  signal(BIONIC_SIGNAL_FDTRACK, [](int) { fdtrack_dump(); });
+  if (Unwinder().Init()) {
+    android_fdtrack_hook_t expected = nullptr;
+    installed = android_fdtrack_compare_exchange_hook(&expected, &fd_hook);
+  }
+}
+
+__attribute__((destructor)) static void dtor() {
+  if (installed) {
+    android_fdtrack_hook_t expected = &fd_hook;
+    android_fdtrack_compare_exchange_hook(&expected, nullptr);
+  }
+}
+
+FdEntry* GetFdEntry(int fd) {
+  if (fd >= 0 && fd < static_cast<int>(kFdTableSize)) {
+    return &stack_traces[fd];
+  }
+  return nullptr;
+}
+
+static void fd_hook(android_fdtrack_event* event) {
+  if (event->type == ANDROID_FDTRACK_EVENT_TYPE_CREATE) {
+    if (FdEntry* entry = GetFdEntry(event->fd); entry) {
+      std::lock_guard<std::mutex> lock(entry->mutex);
+      entry->backtrace.clear();
+      Unwinder().Unwind(&entry->backtrace, kStackDepth);
+    }
+  } else if (event->type == ANDROID_FDTRACK_EVENT_TYPE_CLOSE) {
+    if (FdEntry* entry = GetFdEntry(event->fd); entry) {
+      std::lock_guard<std::mutex> lock(entry->mutex);
+      entry->backtrace.clear();
+    }
+  }
+}
+
+void fdtrack_dump() {
+  if (!installed) {
+    async_safe_format_log(ANDROID_LOG_INFO, "fdtrack", "fdtrack not installed");
+  } else {
+    async_safe_format_log(ANDROID_LOG_INFO, "fdtrack", "fdtrack dumping...");
+  }
+
+  bool prev = android_fdtrack_set_enabled(false);
+  for (int fd = 0; fd < static_cast<int>(stack_traces.size()); ++fd) {
+    FdEntry* entry = GetFdEntry(fd);
+    if (!entry) {
+      continue;
+    }
+
+    std::lock_guard<std::mutex> lock(entry->mutex);
+    if (entry->backtrace.empty()) {
+      continue;
+    }
+
+    async_safe_format_log(ANDROID_LOG_INFO, "fdtrack", "fd %d:", fd);
+    const size_t frame_skip = 2;
+    for (size_t i = frame_skip; i < entry->backtrace.size(); ++i) {
+      auto& frame = entry->backtrace[i];
+      async_safe_format_log(ANDROID_LOG_INFO, "fdtrack", "  %zu: %s+%" PRIu64, i - frame_skip,
+                            frame.function_name.c_str(), frame.function_offset);
+    }
+  }
+  android_fdtrack_set_enabled(prev);
+}
diff --git a/libfdtrack/libfdtrack.map.txt b/libfdtrack/libfdtrack.map.txt
new file mode 100644
index 0000000..7a54c35
--- /dev/null
+++ b/libfdtrack/libfdtrack.map.txt
@@ -0,0 +1,6 @@
+LIBFDTRACK {
+  global:
+    fdtrack_dump;
+  local:
+    *;
+};