diff --git a/libc/bionic/debug_stacktrace.cpp b/libc/bionic/debug_stacktrace.cpp
new file mode 100644
index 0000000..4b080a4
--- /dev/null
+++ b/libc/bionic/debug_stacktrace.cpp
@@ -0,0 +1,112 @@
+/*
+ * 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_stacktrace.h"
+
+#include <dlfcn.h>
+#include <unistd.h>
+#include <unwind.h>
+#include <sys/types.h>
+
+#include "debug_format.h"
+#include "debug_mapinfo.h"
+#include "logd.h"
+
+/* depends how the system includes define this */
+#ifdef HAVE_UNWIND_CONTEXT_STRUCT
+typedef struct _Unwind_Context __unwind_context;
+#else
+typedef _Unwind_Context __unwind_context;
+#endif
+
+static _Unwind_Reason_Code trace_function(__unwind_context* context, void* arg) {
+  stack_crawl_state_t* state = static_cast<stack_crawl_state_t*>(arg);
+  if (state->count) {
+    intptr_t ip = (intptr_t)_Unwind_GetIP(context);
+    if (ip) {
+      state->addrs[0] = ip;
+      state->addrs++;
+      state->count--;
+      return _URC_NO_REASON;
+    }
+  }
+  // If we run out of space to record the address or 0 has been seen, stop
+  // unwinding the stack.
+  return _URC_END_OF_STACK;
+}
+
+__LIBC_HIDDEN__ int get_backtrace(intptr_t* addrs, size_t max_entries) {
+  stack_crawl_state_t state;
+  state.count = max_entries;
+  state.addrs = addrs;
+  _Unwind_Backtrace(trace_function, &state);
+  return max_entries - state.count;
+}
+
+__LIBC_HIDDEN__ void log_backtrace(mapinfo_t* map_info, intptr_t* addrs, size_t c) {
+  intptr_t self_bt[16];
+  if (addrs == NULL) {
+    c = get_backtrace(self_bt, 16);
+    addrs = self_bt;
+  }
+
+  __libc_format_log(ANDROID_LOG_ERROR, "libc",
+                    "*** *** *** *** *** *** *** *** *** *** *** *** *** *** *** ***\n");
+
+  int index = 0;
+  for (size_t i = 0 ; i < c; ++i) {
+    void* offset = 0;
+    const char* symbol = NULL;
+
+    Dl_info info;
+    if (dladdr((void*) addrs[i], &info) != 0) {
+      offset = info.dli_saddr;
+      symbol = info.dli_sname;
+    }
+
+    // This test is a bit sketchy, but it allows us to skip the
+    // stack trace entries due to this debugging code. it works
+    // because those don't have a symbol (they're not exported).
+    if (symbol != NULL || index > 0) {
+      unsigned int rel_pc;
+      const mapinfo_t* mi = mapinfo_find(map_info, addrs[i], &rel_pc);
+      const char* soname = mi ? mi->name : info.dli_fname;
+      if (soname == NULL) {
+        soname = "unknown";
+      }
+      if (symbol) {
+        __libc_format_log(ANDROID_LOG_ERROR, "libc", "          #%02d  pc %08x  %s (%s+0x%x)",
+                          index, rel_pc, soname, symbol, addrs[i] - (intptr_t)offset);
+      } else {
+        __libc_format_log(ANDROID_LOG_ERROR, "libc", "          #%02d  pc %08x  %s",
+                          index, rel_pc, soname);
+      }
+      ++index;
+    }
+  }
+}