diff --git a/libc/bionic/debug_backtrace.cpp b/libc/bionic/debug_backtrace.cpp
new file mode 100644
index 0000000..de3ce08
--- /dev/null
+++ b/libc/bionic/debug_backtrace.cpp
@@ -0,0 +1,175 @@
+/*
+ * Copyright (C) 2012 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 "debug_backtrace.h"
+
+#include <dlfcn.h>
+#include <inttypes.h>
+#include <malloc.h>
+#include <unistd.h>
+#include <unwind.h>
+#include <sys/types.h>
+
+#include "debug_mapinfo.h"
+#include "malloc_debug_disable.h"
+#include "private/libc_logging.h"
+
+#if defined(__LP64__)
+#define PAD_PTR "016" PRIxPTR
+#else
+#define PAD_PTR "08" PRIxPTR
+#endif
+
+typedef struct _Unwind_Context __unwind_context;
+
+extern "C" char* __cxa_demangle(const char*, char*, size_t*, int*);
+
+static mapinfo_t* g_map_info = NULL;
+
+__LIBC_HIDDEN__ void backtrace_startup() {
+  ScopedDisableDebugCalls disable;
+
+  g_map_info = mapinfo_create(getpid());
+}
+
+__LIBC_HIDDEN__ void backtrace_shutdown() {
+  ScopedDisableDebugCalls disable;
+
+  mapinfo_destroy(g_map_info);
+}
+
+struct stack_crawl_state_t {
+  uintptr_t* frames;
+  size_t frame_count;
+  size_t max_depth;
+  bool have_skipped_self;
+
+  stack_crawl_state_t(uintptr_t* frames, size_t max_depth)
+      : frames(frames), frame_count(0), max_depth(max_depth), have_skipped_self(false) {
+  }
+};
+
+static _Unwind_Reason_Code trace_function(__unwind_context* context, void* arg) {
+  stack_crawl_state_t* state = static_cast<stack_crawl_state_t*>(arg);
+
+  uintptr_t ip = _Unwind_GetIP(context);
+
+  // The first stack frame is get_backtrace itself. Skip it.
+  if (ip != 0 && !state->have_skipped_self) {
+    state->have_skipped_self = true;
+    return _URC_NO_REASON;
+  }
+
+  // The instruction pointer is pointing at the instruction after the return
+  // call on all architectures.
+  // Modify the pc to point at the real function.
+  if (ip != 0) {
+#if defined(__arm__)
+    // If the ip is suspiciously low, do nothing to avoid a segfault trying
+    // to access this memory.
+    if (ip >= 4096) {
+      // Check bits [15:11] of the first halfword assuming the instruction
+      // is 32 bits long. If the bits are any of these values, then our
+      // assumption was correct:
+      //  b11101
+      //  b11110
+      //  b11111
+      // Otherwise, this is a 16 bit instruction.
+      uint16_t value = (*reinterpret_cast<uint16_t*>(ip - 2)) >> 11;
+      if (value == 0x1f || value == 0x1e || value == 0x1d) {
+        ip -= 4;
+      } else {
+        ip -= 2;
+      }
+    }
+#elif defined(__aarch64__)
+    // All instructions are 4 bytes long, skip back one instruction.
+    ip -= 4;
+#elif defined(__i386__) || defined(__x86_64__)
+    // It's difficult to decode exactly where the previous instruction is,
+    // so subtract 1 to estimate where the instruction lives.
+    ip--;
+#endif
+  }
+
+  state->frames[state->frame_count++] = ip;
+  return (state->frame_count >= state->max_depth) ? _URC_END_OF_STACK : _URC_NO_REASON;
+}
+
+__LIBC_HIDDEN__ int get_backtrace(uintptr_t* frames, size_t max_depth) {
+  ScopedDisableDebugCalls disable;
+
+  stack_crawl_state_t state(frames, max_depth);
+  _Unwind_Backtrace(trace_function, &state);
+  return state.frame_count;
+}
+
+__LIBC_HIDDEN__ void log_backtrace(uintptr_t* frames, size_t frame_count) {
+  ScopedDisableDebugCalls disable;
+
+  uintptr_t self_bt[16];
+  if (frames == NULL) {
+    frame_count = get_backtrace(self_bt, 16);
+    frames = self_bt;
+  }
+
+  __libc_format_log(ANDROID_LOG_ERROR, "libc",
+                    "*** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***\n");
+
+  for (size_t i = 0 ; i < frame_count; ++i) {
+    uintptr_t offset = 0;
+    const char* symbol = NULL;
+
+    Dl_info info;
+    if (dladdr((void*) frames[i], &info) != 0) {
+      offset = reinterpret_cast<uintptr_t>(info.dli_saddr);
+      symbol = info.dli_sname;
+    }
+
+    uintptr_t rel_pc = offset;
+    const mapinfo_t* mi = (g_map_info != NULL) ? mapinfo_find(g_map_info, frames[i], &rel_pc) : NULL;
+    const char* soname = (mi != NULL) ? mi->name : info.dli_fname;
+    if (soname == NULL) {
+      soname = "<unknown>";
+    }
+    if (symbol != NULL) {
+      char* demangled_symbol = __cxa_demangle(symbol, NULL, NULL, NULL);
+      const char* best_name = (demangled_symbol != NULL) ? demangled_symbol : symbol;
+
+      __libc_format_log(ANDROID_LOG_ERROR, "libc",
+                        "          #%02zd  pc %" PAD_PTR "  %s (%s+%" PRIuPTR ")",
+                        i, rel_pc, soname, best_name, frames[i] - offset);
+
+      free(demangled_symbol);
+    } else {
+      __libc_format_log(ANDROID_LOG_ERROR, "libc",
+                        "          #%02zd  pc %" PAD_PTR "  %s",
+                        i, rel_pc, soname);
+    }
+  }
+}