diff --git a/adb/adb.cpp b/adb/adb.cpp
index 60966d6..19dd03d 100644
--- a/adb/adb.cpp
+++ b/adb/adb.cpp
@@ -334,7 +334,7 @@
 #endif
 
     connection_properties.push_back(android::base::StringPrintf(
-        "features=%s", android::base::Join(supported_features(), ',').c_str()));
+        "features=%s", FeatureSetToString(supported_features()).c_str()));
 
     return android::base::StringPrintf(
         "%s::%s", adb_device_banner,
@@ -396,9 +396,7 @@
             } else if (key == "ro.product.device") {
                 qual_overwrite(&t->device, value);
             } else if (key == "features") {
-                for (const auto& feature : android::base::Split(value, ",")) {
-                    t->add_feature(feature);
-                }
+                t->SetFeatures(value);
             }
         }
     }
@@ -1149,27 +1147,13 @@
         std::string error_msg;
         atransport* t = acquire_one_transport(kCsAny, type, serial, &error_msg);
         if (t != nullptr) {
-            SendOkay(reply_fd, android::base::Join(t->features(), '\n'));
+            SendOkay(reply_fd, FeatureSetToString(t->features()));
         } else {
             SendFail(reply_fd, error_msg);
         }
         return 0;
     }
 
-    if (!strncmp(service, "check-feature:", strlen("check-feature:"))) {
-        std::string error_msg;
-        atransport* t = acquire_one_transport(kCsAny, type, serial, &error_msg);
-        if (t && t->CanUseFeature(service + strlen("check-feature:"))) {
-            // We could potentially extend this to reply with the feature
-            // version if that becomes necessary.
-            SendOkay(reply_fd, "1");
-        } else {
-            // Empty response means unsupported feature.
-            SendOkay(reply_fd, "");
-        }
-        return 0;
-    }
-
     // remove TCP transport
     if (!strncmp(service, "disconnect:", 11)) {
         const std::string address(service + 11);
diff --git a/adb/adb_trace.h b/adb/adb_trace.h
index 623108e..b4155df 100644
--- a/adb/adb_trace.h
+++ b/adb/adb_trace.h
@@ -50,9 +50,7 @@
 #define D(...) \
         do { \
             if (ADB_TRACING) { \
-                int saved_errno = errno; \
                 LOG(INFO) << android::base::StringPrintf(__VA_ARGS__); \
-                errno = saved_errno; \
            } \
         } while (0)
 
diff --git a/adb/commandline.cpp b/adb/commandline.cpp
index d287480..4e93dee 100644
--- a/adb/commandline.cpp
+++ b/adb/commandline.cpp
@@ -36,6 +36,7 @@
 
 #include <base/logging.h>
 #include <base/stringprintf.h>
+#include <base/strings.h>
 
 #if !defined(_WIN32)
 #include <termios.h>
@@ -108,7 +109,9 @@
         "  adb sync [ <directory> ]     - copy host->device only if changed\n"
         "                                 (-l means list but don't copy)\n"
         "  adb shell                    - run remote shell interactively\n"
-        "  adb shell <command>          - run remote shell command\n"
+        "  adb shell [-Tt] <command>    - run remote shell command\n"
+        "                                 (-T disables PTY allocation)\n"
+        "                                 (-t forces PTY allocation)\n"
         "  adb emu <command>            - run emulator console command\n"
         "  adb logcat [ <filter-spec> ] - View device log\n"
         "  adb forward --list           - list all forward socket connections.\n"
@@ -475,9 +478,10 @@
     return nullptr;
 }
 
-static int interactive_shell(bool use_shell_protocol) {
+static int interactive_shell(const std::string& service_string,
+                             bool use_shell_protocol) {
     std::string error;
-    int fd = adb_connect("shell:", &error);
+    int fd = adb_connect(service_string, &error);
     if (fd < 0) {
         fprintf(stderr,"error: %s\n", error.c_str());
         return 1;
@@ -524,18 +528,16 @@
     return android::base::StringPrintf("%s:%s", prefix, command);
 }
 
-// Checks whether the device indicated by |transport_type| and |serial| supports
-// |feature|. Returns the response string, which will be empty if the device
-// could not be found or the feature is not supported.
-static std::string CheckFeature(const std::string& feature,
-                                TransportType transport_type,
+// Returns the FeatureSet for the indicated transport.
+static FeatureSet GetFeatureSet(TransportType transport_type,
                                 const char* serial) {
-    std::string result, error, command("check-feature:" + feature);
-    if (!adb_query(format_host_command(command.c_str(), transport_type, serial),
-                   &result, &error)) {
-        return "";
+    std::string result, error;
+
+    if (adb_query(format_host_command("features", transport_type, serial),
+                  &result, &error)) {
+        return StringToFeatureSet(result);
     }
-    return result;
+    return FeatureSet();
 }
 
 static int adb_download_buffer(const char *service, const char *fn, const void* data, unsigned sz,
@@ -797,9 +799,8 @@
         wait_for_device("wait-for-device", transport_type, serial);
     }
 
-    bool use_shell_protocol = !CheckFeature(kFeatureShell2, transport_type,
-                                            serial).empty();
-    int exit_code = read_and_dump(fd, use_shell_protocol);
+    FeatureSet features = GetFeatureSet(transport_type, serial);
+    int exit_code = read_and_dump(fd, features.count(kFeatureShell2) > 0);
 
     if (adb_close(fd) < 0) {
         PLOG(ERROR) << "failure closing FD " << fd;
@@ -1238,24 +1239,44 @@
     else if (!strcmp(argv[0], "shell") || !strcmp(argv[0], "hell")) {
         char h = (argv[0][0] == 'h');
 
+        FeatureSet features = GetFeatureSet(transport_type, serial);
+
+        bool use_shell_protocol = (features.count(kFeatureShell2) > 0);
+        if (!use_shell_protocol) {
+            D("shell protocol not supported, using raw data transfer");
+        } else {
+            D("using shell protocol");
+        }
+
+        // Parse shell-specific command-line options.
+        // argv[0] is always "shell".
+        --argc;
+        ++argv;
+        std::string shell_type_arg;
+        while (argc) {
+            if (!strcmp(argv[0], "-T") || !strcmp(argv[0], "-t")) {
+                if (features.count(kFeatureShell2) == 0) {
+                    fprintf(stderr, "error: target doesn't support PTY args -Tt\n");
+                    return 1;
+                }
+                shell_type_arg = argv[0];
+                --argc;
+                ++argv;
+            } else {
+                break;
+            }
+        }
+        std::string service_string = android::base::StringPrintf(
+                "shell%s:", shell_type_arg.c_str());
+
         if (h) {
             printf("\x1b[41;33m");
             fflush(stdout);
         }
 
-        bool use_shell_protocol;
-        if (CheckFeature(kFeatureShell2, transport_type, serial).empty()) {
-            D("shell protocol not supported, using raw data transfer");
-            use_shell_protocol = false;
-        } else {
-            D("using shell protocol");
-            use_shell_protocol = true;
-        }
-
-
-        if (argc < 2) {
+        if (!argc) {
             D("starting interactive shell");
-            r = interactive_shell(use_shell_protocol);
+            r = interactive_shell(service_string, use_shell_protocol);
             if (h) {
                 printf("\x1b[0m");
                 fflush(stdout);
@@ -1263,19 +1284,14 @@
             return r;
         }
 
-        std::string cmd = "shell:";
-        --argc;
-        ++argv;
-        while (argc-- > 0) {
-            // We don't escape here, just like ssh(1). http://b/20564385.
-            cmd += *argv++;
-            if (*argv) cmd += " ";
-        }
+        // We don't escape here, just like ssh(1). http://b/20564385.
+        service_string += android::base::Join(
+                std::vector<const char*>(argv, argv + argc), ' ');
 
         while (true) {
-            D("non-interactive shell loop. cmd=%s", cmd.c_str());
+            D("non-interactive shell loop. cmd=%s", service_string.c_str());
             std::string error;
-            int fd = adb_connect(cmd, &error);
+            int fd = adb_connect(service_string, &error);
             int r;
             if (fd >= 0) {
                 D("about to read_and_dump(fd=%d)", fd);
@@ -1545,7 +1561,14 @@
         return 0;
     }
     else if (!strcmp(argv[0], "features")) {
-        return adb_query_command(format_host_command("features", transport_type, serial));
+        // Only list the features common to both the adb client and the device.
+        FeatureSet features = GetFeatureSet(transport_type, serial);
+        for (const std::string& name : features) {
+            if (supported_features().count(name) > 0) {
+                printf("%s\n", name.c_str());
+            }
+        }
+        return 0;
     }
 
     usage();
diff --git a/adb/services.cpp b/adb/services.cpp
index d128efc..d0494ec 100644
--- a/adb/services.cpp
+++ b/adb/services.cpp
@@ -194,7 +194,39 @@
     adb_close(fd);
 }
 
-#endif
+// Shell service string can look like:
+//   shell[args]:[command]
+// Currently the only supported args are -T (force raw) and -t (force PTY).
+static int ShellService(const std::string& args, const atransport* transport) {
+    size_t delimiter_index = args.find(':');
+    if (delimiter_index == std::string::npos) {
+        LOG(ERROR) << "No ':' found in shell service arguments: " << args;
+        return -1;
+    }
+    const std::string service_args = args.substr(0, delimiter_index);
+    const std::string command = args.substr(delimiter_index + 1);
+
+    SubprocessType type;
+    if (service_args.empty()) {
+        // Default: use PTY for interactive, raw for non-interactive.
+        type = (command.empty() ? SubprocessType::kPty : SubprocessType::kRaw);
+    } else if (service_args == "-T") {
+        type = SubprocessType::kRaw;
+    } else if (service_args == "-t") {
+        type = SubprocessType::kPty;
+    } else {
+        LOG(ERROR) << "Unsupported shell service arguments: " << args;
+        return -1;
+    }
+
+    SubprocessProtocol protocol =
+            (transport->CanUseFeature(kFeatureShell2) ? SubprocessProtocol::kShell
+                                                      : SubprocessProtocol::kNone);
+
+    return StartSubprocess(command.c_str(), type, protocol);
+}
+
+#endif  // !ADB_HOST
 
 static int create_service_thread(void (*func)(int, void *), void *cookie)
 {
@@ -265,14 +297,8 @@
         ret = create_service_thread(framebuffer_service, 0);
     } else if (!strncmp(name, "jdwp:", 5)) {
         ret = create_jdwp_connection_fd(atoi(name+5));
-    } else if(!strncmp(name, "shell:", 6)) {
-        const char* args = name + 6;
-        // Use raw for non-interactive, PTY for interactive.
-        SubprocessType type = (*args ? SubprocessType::kRaw : SubprocessType::kPty);
-        SubprocessProtocol protocol =
-                (transport->CanUseFeature(kFeatureShell2) ? SubprocessProtocol::kShell
-                                                          : SubprocessProtocol::kNone);
-        ret = StartSubprocess(args, type, protocol);
+    } else if(!strncmp(name, "shell", 5)) {
+        ret = ShellService(name + 5, transport);
     } else if(!strncmp(name, "exec:", 5)) {
         ret = StartSubprocess(name + 5, SubprocessType::kRaw,
                               SubprocessProtocol::kNone);
diff --git a/adb/transport.cpp b/adb/transport.cpp
index db9236e..402546b 100644
--- a/adb/transport.cpp
+++ b/adb/transport.cpp
@@ -779,27 +779,37 @@
     return max_payload;
 }
 
-// Do not use any of [:;=,] in feature strings, they have special meaning
-// in the connection banner.
-// TODO(dpursell): add this in once we can pass features through to the client.
-const char kFeatureShell2[] = "shell_2";
+namespace {
 
-// The list of features supported by the current system. Will be sent to the
-// other side of the connection in the banner.
-static const FeatureSet gSupportedFeatures = {
-        kFeatureShell2,
-};
+constexpr char kFeatureStringDelimiter = ',';
+
+}  // namespace
 
 const FeatureSet& supported_features() {
-    return gSupportedFeatures;
+    // Local static allocation to avoid global non-POD variables.
+    static const FeatureSet* features = new FeatureSet{
+        kFeatureShell2
+    };
+
+    return *features;
+}
+
+std::string FeatureSetToString(const FeatureSet& features) {
+    return android::base::Join(features, kFeatureStringDelimiter);
+}
+
+FeatureSet StringToFeatureSet(const std::string& features_string) {
+    auto names = android::base::Split(features_string,
+                                      {kFeatureStringDelimiter});
+    return FeatureSet(names.begin(), names.end());
 }
 
 bool atransport::has_feature(const std::string& feature) const {
     return features_.count(feature) > 0;
 }
 
-void atransport::add_feature(const std::string& feature) {
-    features_.insert(feature);
+void atransport::SetFeatures(const std::string& features_string) {
+    features_ = StringToFeatureSet(features_string);
 }
 
 bool atransport::CanUseFeature(const std::string& feature) const {
@@ -855,9 +865,6 @@
         append_transport_info(result, "product:", t->product, false);
         append_transport_info(result, "model:", t->model, true);
         append_transport_info(result, "device:", t->device, false);
-        append_transport_info(result, "features:",
-                              android::base::Join(t->features(), ',').c_str(),
-                              false);
     }
     *result += '\n';
 }
diff --git a/adb/transport.h b/adb/transport.h
index 999922a..0ec8ceb 100644
--- a/adb/transport.h
+++ b/adb/transport.h
@@ -29,7 +29,13 @@
 
 const FeatureSet& supported_features();
 
-const extern char kFeatureShell2[];
+// Encodes and decodes FeatureSet objects into human-readable strings.
+std::string FeatureSetToString(const FeatureSet& features);
+FeatureSet StringToFeatureSet(const std::string& features_string);
+
+// Do not use any of [:;=,] in feature strings, they have special meaning
+// in the connection banner.
+constexpr char kFeatureShell2[] = "shell_2";
 
 class atransport {
 public:
@@ -85,12 +91,14 @@
     int get_protocol_version() const;
     size_t get_max_payload() const;
 
-    inline const FeatureSet features() const {
+    const FeatureSet& features() const {
         return features_;
     }
 
     bool has_feature(const std::string& feature) const;
-    void add_feature(const std::string& feature);
+
+    // Loads the transport's feature set from the given string.
+    void SetFeatures(const std::string& features_string);
 
     // Returns true if both we and the other end of the transport support the
     // feature.
diff --git a/adb/transport_test.cpp b/adb/transport_test.cpp
index 10872ac..7d69c3e 100644
--- a/adb/transport_test.cpp
+++ b/adb/transport_test.cpp
@@ -144,23 +144,29 @@
     ASSERT_EQ(0, count);
 }
 
-TEST(transport, add_feature) {
+TEST(transport, SetFeatures) {
     atransport t;
     ASSERT_EQ(0U, t.features().size());
 
-    t.add_feature("foo");
+    t.SetFeatures(FeatureSetToString(FeatureSet{"foo"}));
     ASSERT_EQ(1U, t.features().size());
     ASSERT_TRUE(t.has_feature("foo"));
 
-    t.add_feature("bar");
+    t.SetFeatures(FeatureSetToString(FeatureSet{"foo", "bar"}));
     ASSERT_EQ(2U, t.features().size());
     ASSERT_TRUE(t.has_feature("foo"));
     ASSERT_TRUE(t.has_feature("bar"));
 
-    t.add_feature("foo");
+    t.SetFeatures(FeatureSetToString(FeatureSet{"foo", "bar", "foo"}));
     ASSERT_EQ(2U, t.features().size());
     ASSERT_TRUE(t.has_feature("foo"));
     ASSERT_TRUE(t.has_feature("bar"));
+
+    t.SetFeatures(FeatureSetToString(FeatureSet{"bar", "baz"}));
+    ASSERT_EQ(2U, t.features().size());
+    ASSERT_FALSE(t.has_feature("foo"));
+    ASSERT_TRUE(t.has_feature("bar"));
+    ASSERT_TRUE(t.has_feature("baz"));
 }
 
 TEST(transport, parse_banner_no_features) {
diff --git a/base/include/base/logging.h b/base/include/base/logging.h
index 283a7bc..30f6906 100644
--- a/base/include/base/logging.h
+++ b/base/include/base/logging.h
@@ -87,30 +87,64 @@
 // Replace the current logger.
 extern void SetLogger(LogFunction&& logger);
 
+// Get the minimum severity level for logging.
+extern LogSeverity GetMinimumLogSeverity();
+
+class ErrnoRestorer {
+ public:
+  ErrnoRestorer()
+      : saved_errno_(errno) {
+  }
+
+  ~ErrnoRestorer() {
+    errno = saved_errno_;
+  }
+
+  // Allow this object to evaluate to false which is useful in macros.
+  operator bool() const {
+    return false;
+  }
+
+ private:
+  const int saved_errno_;
+
+  DISALLOW_COPY_AND_ASSIGN(ErrnoRestorer);
+};
+
 // Logs a message to logcat on Android otherwise to stderr. If the severity is
 // FATAL it also causes an abort. For example:
 //
 //     LOG(FATAL) << "We didn't expect to reach here";
-#define LOG(severity)                                                       \
-  ::android::base::LogMessage(__FILE__, __LINE__, ::android::base::DEFAULT, \
-                              ::android::base::severity, -1).stream()
+#define LOG(severity) LOG_TO(DEFAULT, severity)
 
 // Logs a message to logcat with the specified log ID on Android otherwise to
 // stderr. If the severity is FATAL it also causes an abort.
-#define LOG_TO(dest, severity)                                           \
-  ::android::base::LogMessage(__FILE__, __LINE__, ::android::base::dest, \
-                              ::android::base::severity, -1).stream()
+// Use an if-else statement instead of just an if statement here. So if there is a
+// else statement after LOG() macro, it won't bind to the if statement in the macro.
+// do-while(0) statement doesn't work here. Because we need to support << operator
+// following the macro, like "LOG(DEBUG) << xxx;".
+#define LOG_TO(dest, severity)                                                      \
+  if (LIKELY(::android::base::severity < ::android::base::GetMinimumLogSeverity())) \
+    ;                                                                               \
+  else                                                                              \
+    ::android::base::ErrnoRestorer() ? *(std::ostream*)nullptr :                    \
+      ::android::base::LogMessage(__FILE__, __LINE__,                               \
+          ::android::base::dest,                                                    \
+          ::android::base::severity, -1).stream()
 
 // A variant of LOG that also logs the current errno value. To be used when
 // library calls fail.
-#define PLOG(severity)                                                      \
-  ::android::base::LogMessage(__FILE__, __LINE__, ::android::base::DEFAULT, \
-                              ::android::base::severity, errno).stream()
+#define PLOG(severity) PLOG_TO(DEFAULT, severity)
 
 // Behaves like PLOG, but logs to the specified log ID.
-#define PLOG_TO(dest, severity)                                          \
-  ::android::base::LogMessage(__FILE__, __LINE__, ::android::base::dest, \
-                              ::android::base::severity, errno).stream()
+#define PLOG_TO(dest, severity)                                                     \
+  if (LIKELY(::android::base::severity < ::android::base::GetMinimumLogSeverity())) \
+    ;                                                                               \
+  else                                                                              \
+    ::android::base::ErrnoRestorer() ? *(std::ostream*)nullptr :                    \
+      ::android::base::LogMessage(__FILE__, __LINE__,                               \
+          ::android::base::dest,                                                    \
+          ::android::base::severity, errno).stream()
 
 // Marker that code is yet to be implemented.
 #define UNIMPLEMENTED(level) \
@@ -122,11 +156,13 @@
 //
 //     CHECK(false == true) results in a log message of
 //       "Check failed: false == true".
-#define CHECK(x)                                                            \
-  if (UNLIKELY(!(x)))                                                       \
-  ::android::base::LogMessage(__FILE__, __LINE__, ::android::base::DEFAULT, \
-                              ::android::base::FATAL, -1).stream()          \
-      << "Check failed: " #x << " "
+#define CHECK(x)                                                              \
+  if (LIKELY((x)))                                                            \
+    ;                                                                         \
+  else                                                                        \
+    ::android::base::LogMessage(__FILE__, __LINE__, ::android::base::DEFAULT, \
+                                ::android::base::FATAL, -1).stream()          \
+        << "Check failed: " #x << " "
 
 // Helper for CHECK_xx(x,y) macros.
 #define CHECK_OP(LHS, RHS, OP)                                              \
@@ -153,7 +189,9 @@
 
 // Helper for CHECK_STRxx(s1,s2) macros.
 #define CHECK_STROP(s1, s2, sense)                                         \
-  if (UNLIKELY((strcmp(s1, s2) == 0) != sense))                            \
+  if (LIKELY((strcmp(s1, s2) == 0) == sense))                              \
+    ;                                                                      \
+  else                                                                     \
     LOG(FATAL) << "Check failed: "                                         \
                << "\"" << s1 << "\""                                       \
                << (sense ? " == " : " != ") << "\"" << s2 << "\""
diff --git a/base/logging.cpp b/base/logging.cpp
index e9e06df..6bfaaec 100644
--- a/base/logging.cpp
+++ b/base/logging.cpp
@@ -139,6 +139,10 @@
 static LogSeverity gMinimumLogSeverity = INFO;
 static std::unique_ptr<std::string> gProgramInvocationName;
 
+LogSeverity GetMinimumLogSeverity() {
+  return gMinimumLogSeverity;
+}
+
 static const char* ProgramInvocationName() {
   if (gProgramInvocationName == nullptr) {
     gProgramInvocationName.reset(new std::string(getprogname()));
@@ -200,20 +204,6 @@
   InitLogging(argv);
 }
 
-// TODO: make this public; it's independently useful.
-class ErrnoRestorer {
- public:
-  ErrnoRestorer(int saved_errno) : saved_errno_(saved_errno) {
-  }
-
-  ~ErrnoRestorer() {
-    errno = saved_errno_;
-  }
-
- private:
-  const int saved_errno_;
-};
-
 void InitLogging(char* argv[]) {
   if (gInitialized) {
     return;
@@ -286,13 +276,12 @@
 class LogMessageData {
  public:
   LogMessageData(const char* file, unsigned int line, LogId id,
-                 LogSeverity severity, int error, int saved_errno)
+                 LogSeverity severity, int error)
       : file_(GetFileBasename(file)),
         line_number_(line),
         id_(id),
         severity_(severity),
-        error_(error),
-        errno_restorer_(saved_errno) {
+        error_(error) {
   }
 
   const char* GetFile() const {
@@ -330,39 +319,38 @@
   const LogId id_;
   const LogSeverity severity_;
   const int error_;
-  ErrnoRestorer errno_restorer_;
 
   DISALLOW_COPY_AND_ASSIGN(LogMessageData);
 };
 
 LogMessage::LogMessage(const char* file, unsigned int line, LogId id,
                        LogSeverity severity, int error)
-    : data_(new LogMessageData(file, line, id, severity, error, errno)) {
+    : data_(new LogMessageData(file, line, id, severity, error)) {
 }
 
 LogMessage::~LogMessage() {
-  if (data_->GetSeverity() < gMinimumLogSeverity) {
-    return;  // No need to format something we're not going to output.
-  }
-
   // Finish constructing the message.
   if (data_->GetError() != -1) {
     data_->GetBuffer() << ": " << strerror(data_->GetError());
   }
   std::string msg(data_->ToString());
 
-  if (msg.find('\n') == std::string::npos) {
-    LogLine(data_->GetFile(), data_->GetLineNumber(), data_->GetId(),
-            data_->GetSeverity(), msg.c_str());
-  } else {
-    msg += '\n';
-    size_t i = 0;
-    while (i < msg.size()) {
-      size_t nl = msg.find('\n', i);
-      msg[nl] = '\0';
+  {
+    // Do the actual logging with the lock held.
+    lock_guard<mutex> lock(logging_lock);
+    if (msg.find('\n') == std::string::npos) {
       LogLine(data_->GetFile(), data_->GetLineNumber(), data_->GetId(),
-              data_->GetSeverity(), &msg[i]);
-      i = nl + 1;
+              data_->GetSeverity(), msg.c_str());
+    } else {
+      msg += '\n';
+      size_t i = 0;
+      while (i < msg.size()) {
+        size_t nl = msg.find('\n', i);
+        msg[nl] = '\0';
+        LogLine(data_->GetFile(), data_->GetLineNumber(), data_->GetId(),
+                data_->GetSeverity(), &msg[i]);
+        i = nl + 1;
+      }
     }
   }
 
@@ -382,7 +370,6 @@
 void LogMessage::LogLine(const char* file, unsigned int line, LogId id,
                          LogSeverity severity, const char* message) {
   const char* tag = ProgramInvocationName();
-  lock_guard<mutex> lock(logging_lock);
   gLogger(id, severity, tag, file, line, message);
 }
 
diff --git a/base/logging_test.cpp b/base/logging_test.cpp
index c12dfa5..9cf1aad 100644
--- a/base/logging_test.cpp
+++ b/base/logging_test.cpp
@@ -18,6 +18,10 @@
 
 #include <libgen.h>
 
+#if defined(_WIN32)
+#include <signal.h>
+#endif
+
 #include <regex>
 #include <string>
 
@@ -49,6 +53,11 @@
 
  private:
   void init() {
+#if defined(_WIN32)
+    // On Windows, stderr is often buffered, so make sure it is unbuffered so
+    // that we can immediately read back what was written to stderr.
+    ASSERT_EQ(0, setvbuf(stderr, NULL, _IONBF, 0));
+#endif
     old_stderr_ = dup(STDERR_FILENO);
     ASSERT_NE(-1, old_stderr_);
     ASSERT_NE(-1, dup2(fd(), STDERR_FILENO));
@@ -57,21 +66,58 @@
   void reset() {
     ASSERT_NE(-1, dup2(old_stderr_, STDERR_FILENO));
     ASSERT_EQ(0, close(old_stderr_));
+    // Note: cannot restore prior setvbuf() setting.
   }
 
   TemporaryFile temp_file_;
   int old_stderr_;
 };
 
+#if defined(_WIN32)
+static void ExitSignalAbortHandler(int) {
+  _exit(3);
+}
+#endif
+
+static void SuppressAbortUI() {
+#if defined(_WIN32)
+  // We really just want to call _set_abort_behavior(0, _CALL_REPORTFAULT) to
+  // suppress the Windows Error Reporting dialog box, but that API is not
+  // available in the OS-supplied C Runtime, msvcrt.dll, that we currently
+  // use (it is available in the Visual Studio C runtime).
+  //
+  // Instead, we setup a SIGABRT handler, which is called in abort() right
+  // before calling Windows Error Reporting. In the handler, we exit the
+  // process just like abort() does.
+  ASSERT_NE(SIG_ERR, signal(SIGABRT, ExitSignalAbortHandler));
+#endif
+}
+
 TEST(logging, CHECK) {
-  ASSERT_DEATH(CHECK(false), "Check failed: false ");
+  ASSERT_DEATH({SuppressAbortUI(); CHECK(false);}, "Check failed: false ");
   CHECK(true);
 
-  ASSERT_DEATH(CHECK_EQ(0, 1), "Check failed: 0 == 1 ");
+  ASSERT_DEATH({SuppressAbortUI(); CHECK_EQ(0, 1);}, "Check failed: 0 == 1 ");
   CHECK_EQ(0, 0);
 
-  ASSERT_DEATH(CHECK_STREQ("foo", "bar"), R"(Check failed: "foo" == "bar")");
+  ASSERT_DEATH({SuppressAbortUI(); CHECK_STREQ("foo", "bar");},
+               R"(Check failed: "foo" == "bar")");
   CHECK_STREQ("foo", "foo");
+
+  // Test whether CHECK() and CHECK_STREQ() have a dangling if with no else.
+  bool flag = false;
+  if (true)
+    CHECK(true);
+  else
+    flag = true;
+  EXPECT_FALSE(flag) << "CHECK macro probably has a dangling if with no else";
+
+  flag = false;
+  if (true)
+    CHECK_STREQ("foo", "foo");
+  else
+    flag = true;
+  EXPECT_FALSE(flag) << "CHECK_STREQ probably has a dangling if with no else";
 }
 
 std::string make_log_pattern(android::base::LogSeverity severity,
@@ -85,7 +131,7 @@
 }
 
 TEST(logging, LOG) {
-  ASSERT_DEATH(LOG(FATAL) << "foobar", "foobar");
+  ASSERT_DEATH({SuppressAbortUI(); LOG(FATAL) << "foobar";}, "foobar");
 
   // We can't usefully check the output of any of these on Windows because we
   // don't have std::regex, but we can at least make sure we printed at least as
@@ -148,6 +194,50 @@
     ASSERT_TRUE(std::regex_search(output, message_regex)) << output;
 #endif
   }
+
+  // Test whether LOG() saves and restores errno.
+  {
+    CapturedStderr cap;
+    errno = 12345;
+    LOG(INFO) << (errno = 67890);
+    EXPECT_EQ(12345, errno) << "errno was not restored";
+
+    ASSERT_EQ(0, lseek(cap.fd(), SEEK_SET, 0));
+
+    std::string output;
+    android::base::ReadFdToString(cap.fd(), &output);
+    EXPECT_NE(nullptr, strstr(output.c_str(), "67890")) << output;
+
+#if !defined(_WIN32)
+    std::regex message_regex(
+        make_log_pattern(android::base::INFO, "67890"));
+    ASSERT_TRUE(std::regex_search(output, message_regex)) << output;
+#endif
+  }
+
+  // Test whether LOG() has a dangling if with no else.
+  {
+    CapturedStderr cap;
+
+    // Do the test two ways: once where we hypothesize that LOG()'s if
+    // will evaluate to true (when severity is high enough) and once when we
+    // expect it to evaluate to false (when severity is not high enough).
+    bool flag = false;
+    if (true)
+      LOG(INFO) << "foobar";
+    else
+      flag = true;
+
+    EXPECT_FALSE(flag) << "LOG macro probably has a dangling if with no else";
+
+    flag = false;
+    if (true)
+      LOG(VERBOSE) << "foobar";
+    else
+      flag = true;
+
+    EXPECT_FALSE(flag) << "LOG macro probably has a dangling if with no else";
+  }
 }
 
 TEST(logging, PLOG) {
diff --git a/debuggerd/Android.mk b/debuggerd/Android.mk
index f7a5f82..de0f943 100644
--- a/debuggerd/Android.mk
+++ b/debuggerd/Android.mk
@@ -99,6 +99,7 @@
 debuggerd_cpp_flags := \
     $(common_cppflags) \
     -Wno-missing-field-initializers \
+    -fno-rtti \
 
 # Only build the host tests on linux.
 ifeq ($(HOST_OS),linux)
diff --git a/include/backtrace/Backtrace.h b/include/backtrace/Backtrace.h
index 290682a..f440bd2 100644
--- a/include/backtrace/Backtrace.h
+++ b/include/backtrace/Backtrace.h
@@ -52,6 +52,12 @@
 typedef ucontext ucontext_t;
 #endif
 
+struct backtrace_stackinfo_t {
+  uint64_t start;
+  uint64_t end;
+  const uint8_t* data;
+};
+
 class Backtrace {
 public:
   // Create the correct Backtrace object based on what is to be unwound.
@@ -66,6 +72,14 @@
   // If map is not NULL, the map is still owned by the caller.
   static Backtrace* Create(pid_t pid, pid_t tid, BacktraceMap* map = NULL);
 
+  // Create an offline Backtrace object that can be used to do an unwind without a process
+  // that is still running. If cache_file is set to true, then elf information will be cached
+  // for this call. The cached information survives until the calling process ends. This means
+  // that subsequent calls to create offline Backtrace objects will continue to use the same
+  // cache. It also assumes that the elf files used for each offline unwind are the same.
+  static Backtrace* CreateOffline(pid_t pid, pid_t tid, BacktraceMap* map,
+                                  const backtrace_stackinfo_t& stack, bool cache_file = false);
+
   virtual ~Backtrace();
 
   // Get the current stack trace and store in the backtrace_ structure.
diff --git a/include/backtrace/BacktraceMap.h b/include/backtrace/BacktraceMap.h
index bb18aa2..2373c45 100644
--- a/include/backtrace/BacktraceMap.h
+++ b/include/backtrace/BacktraceMap.h
@@ -31,6 +31,7 @@
 
 #include <deque>
 #include <string>
+#include <vector>
 
 struct backtrace_map_t {
   uintptr_t start = 0;
@@ -48,6 +49,8 @@
   // is unsupported.
   static BacktraceMap* Create(pid_t pid, bool uncached = false);
 
+  static BacktraceMap* Create(pid_t pid, const std::vector<backtrace_map_t>& maps);
+
   virtual ~BacktraceMap();
 
   // Fill in the map data structure for the given address.
diff --git a/libbacktrace/Android.build.mk b/libbacktrace/Android.build.mk
index 4983b55..8e63dab 100644
--- a/libbacktrace/Android.build.mk
+++ b/libbacktrace/Android.build.mk
@@ -69,7 +69,10 @@
     $($(module)_ldlibs) \
     $($(module)_ldlibs_$(build_type)) \
 
+LOCAL_STRIP_MODULE := $($(module)_strip_module)
+
 ifeq ($(build_type),target)
+  include $(LLVM_DEVICE_BUILD_MK)
   include $(BUILD_$(build_target))
 endif
 
@@ -77,6 +80,7 @@
   # Only build if host builds are supported.
   ifeq ($(build_host),true)
     LOCAL_CFLAGS += -Wno-extern-c-compat -fno-omit-frame-pointer
+    include $(LLVM_HOST_BUILD_MK)
     include $(BUILD_HOST_$(build_target))
   endif
 endif
diff --git a/libbacktrace/Android.mk b/libbacktrace/Android.mk
index 395d677..9c6742e 100644
--- a/libbacktrace/Android.mk
+++ b/libbacktrace/Android.mk
@@ -25,6 +25,7 @@
 
 libbacktrace_common_cppflags := \
 	-std=gnu++11 \
+	-I external/libunwind/include/tdep \
 
 # The latest clang (r230699) does not allow SP/PC to be declared in inline asm lists.
 libbacktrace_common_clang_cflags += \
@@ -37,6 +38,9 @@
 endif
 endif
 
+LLVM_ROOT_PATH := external/llvm
+include $(LLVM_ROOT_PATH)/llvm.mk
+
 #-------------------------------------------------------------------------
 # The libbacktrace library.
 #-------------------------------------------------------------------------
@@ -44,6 +48,7 @@
 	Backtrace.cpp \
 	BacktraceCurrent.cpp \
 	BacktraceMap.cpp \
+	BacktraceOffline.cpp \
 	BacktracePtrace.cpp \
 	thread_utils.c \
 	ThreadEntry.cpp \
@@ -56,6 +61,20 @@
 	liblog \
 	libunwind \
 
+# Use shared llvm library on device to save space.
+libbacktrace_shared_libraries_target := \
+	libLLVM \
+
+# Use static llvm libraries on host to remove dependency on 32-bit llvm shared library
+# which is not included in the prebuilt.
+libbacktrace_static_libraries_host := \
+	libLLVMObject \
+	libLLVMBitReader \
+	libLLVMMC \
+	libLLVMMCParser \
+	libLLVMCore \
+	libLLVMSupport \
+
 libbacktrace_ldlibs_host := \
 	-lpthread \
 	-lrt \
@@ -86,6 +105,8 @@
 libbacktrace_test_src_files := \
 	backtrace_testlib.c \
 
+libbacktrace_test_strip_module := false
+
 module := libbacktrace_test
 module_tag := debug
 build_type := target
@@ -107,6 +128,7 @@
 	-DENABLE_PSS_TESTS \
 
 backtrace_test_src_files := \
+	backtrace_offline_test.cpp \
 	backtrace_test.cpp \
 	GetPss.cpp \
 	thread_utils.c \
@@ -120,6 +142,7 @@
 	libbacktrace \
 	libbase \
 	libcutils \
+	libunwind \
 
 backtrace_test_shared_libraries_target += \
 	libdl \
@@ -127,6 +150,8 @@
 backtrace_test_ldlibs_host += \
 	-ldl \
 
+backtrace_test_strip_module := false
+
 module := backtrace_test
 module_tag := debug
 build_type := target
diff --git a/libbacktrace/Backtrace.cpp b/libbacktrace/Backtrace.cpp
index 97f0ef4..9ead452 100644
--- a/libbacktrace/Backtrace.cpp
+++ b/libbacktrace/Backtrace.cpp
@@ -30,6 +30,7 @@
 #include <cutils/threads.h>
 
 #include "BacktraceLog.h"
+#include "BacktraceOffline.h"
 #include "thread_utils.h"
 #include "UnwindCurrent.h"
 #include "UnwindPtrace.h"
@@ -140,3 +141,8 @@
     return new UnwindPtrace(pid, tid, map);
   }
 }
+
+Backtrace* Backtrace::CreateOffline(pid_t pid, pid_t tid, BacktraceMap* map,
+                                    const backtrace_stackinfo_t& stack, bool cache_file) {
+  return new BacktraceOffline(pid, tid, map, stack, cache_file);
+}
diff --git a/libbacktrace/BacktraceMap.cpp b/libbacktrace/BacktraceMap.cpp
index ca47f67..eac20fe 100644
--- a/libbacktrace/BacktraceMap.cpp
+++ b/libbacktrace/BacktraceMap.cpp
@@ -144,3 +144,13 @@
   return map;
 }
 #endif
+
+BacktraceMap* BacktraceMap::Create(pid_t pid, const std::vector<backtrace_map_t>& maps) {
+    BacktraceMap* backtrace_map = new BacktraceMap(pid);
+    backtrace_map->maps_.insert(backtrace_map->maps_.begin(), maps.begin(), maps.end());
+    std::sort(backtrace_map->maps_.begin(), backtrace_map->maps_.end(),
+            [](const backtrace_map_t& map1, const backtrace_map_t& map2) {
+              return map1.start < map2.start;
+            });
+    return backtrace_map;
+}
diff --git a/libbacktrace/BacktraceOffline.cpp b/libbacktrace/BacktraceOffline.cpp
new file mode 100644
index 0000000..27dfb83
--- /dev/null
+++ b/libbacktrace/BacktraceOffline.cpp
@@ -0,0 +1,636 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "BacktraceOffline.h"
+
+extern "C" {
+#define UNW_REMOTE_ONLY
+#include <dwarf.h>
+}
+
+#include <stdint.h>
+#include <string.h>
+#include <sys/types.h>
+#include <ucontext.h>
+#include <unistd.h>
+
+#include <string>
+#include <vector>
+
+#include <backtrace/Backtrace.h>
+#include <backtrace/BacktraceMap.h>
+
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunused-parameter"
+
+#include <llvm/ADT/StringRef.h>
+#include <llvm/Object/Binary.h>
+#include <llvm/Object/ELFObjectFile.h>
+#include <llvm/Object/ObjectFile.h>
+
+#pragma clang diagnostic pop
+
+#include "BacktraceLog.h"
+
+void Space::Clear() {
+  start = 0;
+  end = 0;
+  data = nullptr;
+}
+
+size_t Space::Read(uint64_t addr, uint8_t* buffer, size_t size) {
+  if (addr >= start && addr < end) {
+    size_t read_size = std::min(size, static_cast<size_t>(end - addr));
+    memcpy(buffer, data + (addr - start), read_size);
+    return read_size;
+  }
+  return 0;
+}
+
+static int FindProcInfo(unw_addr_space_t addr_space, unw_word_t ip, unw_proc_info* proc_info,
+                        int need_unwind_info, void* arg) {
+  BacktraceOffline* backtrace = reinterpret_cast<BacktraceOffline*>(arg);
+  bool result = backtrace->FindProcInfo(addr_space, ip, proc_info, need_unwind_info);
+  return result ? 0 : -UNW_EINVAL;
+}
+
+static void PutUnwindInfo(unw_addr_space_t, unw_proc_info_t*, void*) {
+}
+
+static int GetDynInfoListAddr(unw_addr_space_t, unw_word_t*, void*) {
+  return -UNW_ENOINFO;
+}
+
+static int AccessMem(unw_addr_space_t, unw_word_t addr, unw_word_t* value, int write, void* arg) {
+  if (write == 1) {
+    return -UNW_EINVAL;
+  }
+  BacktraceOffline* backtrace = reinterpret_cast<BacktraceOffline*>(arg);
+  *value = 0;
+  size_t read_size = backtrace->Read(addr, reinterpret_cast<uint8_t*>(value), sizeof(unw_word_t));
+  // Strictly we should check if read_size matches sizeof(unw_word_t), but it is possible in
+  // .eh_frame_hdr that the section can end at a position not aligned in sizeof(unw_word_t), and
+  // we should permit the read at the end of the section.
+  return (read_size > 0u ? 0 : -UNW_EINVAL);
+}
+
+static int AccessReg(unw_addr_space_t, unw_regnum_t unwind_reg, unw_word_t* value, int write,
+                     void* arg) {
+  if (write == 1) {
+    return -UNW_EINVAL;
+  }
+  BacktraceOffline* backtrace = reinterpret_cast<BacktraceOffline*>(arg);
+  uint64_t reg_value;
+  bool result = backtrace->ReadReg(unwind_reg, &reg_value);
+  if (result) {
+    *value = static_cast<unw_word_t>(reg_value);
+  }
+  return result ? 0 : -UNW_EINVAL;
+}
+
+static int AccessFpReg(unw_addr_space_t, unw_regnum_t, unw_fpreg_t*, int, void*) {
+  return -UNW_EINVAL;
+}
+
+static int Resume(unw_addr_space_t, unw_cursor_t*, void*) {
+  return -UNW_EINVAL;
+}
+
+static int GetProcName(unw_addr_space_t, unw_word_t, char*, size_t, unw_word_t*, void*) {
+  return -UNW_EINVAL;
+}
+
+static unw_accessors_t accessors = {
+    .find_proc_info = FindProcInfo,
+    .put_unwind_info = PutUnwindInfo,
+    .get_dyn_info_list_addr = GetDynInfoListAddr,
+    .access_mem = AccessMem,
+    .access_reg = AccessReg,
+    .access_fpreg = AccessFpReg,
+    .resume = Resume,
+    .get_proc_name = GetProcName,
+};
+
+bool BacktraceOffline::Unwind(size_t num_ignore_frames, ucontext_t* context) {
+  if (context == nullptr) {
+    BACK_LOGW("The context is needed for offline backtracing.");
+    return false;
+  }
+  context_ = context;
+
+  unw_addr_space_t addr_space = unw_create_addr_space(&accessors, 0);
+  unw_cursor_t cursor;
+  int ret = unw_init_remote(&cursor, addr_space, this);
+  if (ret != 0) {
+    BACK_LOGW("unw_init_remote failed %d", ret);
+    unw_destroy_addr_space(addr_space);
+    return false;
+  }
+  size_t num_frames = 0;
+  do {
+    unw_word_t pc;
+    ret = unw_get_reg(&cursor, UNW_REG_IP, &pc);
+    if (ret < 0) {
+      BACK_LOGW("Failed to read IP %d", ret);
+      break;
+    }
+    unw_word_t sp;
+    ret = unw_get_reg(&cursor, UNW_REG_SP, &sp);
+    if (ret < 0) {
+      BACK_LOGW("Failed to read SP %d", ret);
+      break;
+    }
+
+    if (num_ignore_frames == 0) {
+      frames_.resize(num_frames + 1);
+      backtrace_frame_data_t* frame = &frames_[num_frames];
+      frame->num = num_frames;
+      frame->pc = static_cast<uintptr_t>(pc);
+      frame->sp = static_cast<uintptr_t>(sp);
+      frame->stack_size = 0;
+
+      if (num_frames > 0) {
+        backtrace_frame_data_t* prev = &frames_[num_frames - 1];
+        prev->stack_size = frame->sp - prev->sp;
+      }
+      frame->func_name = GetFunctionName(frame->pc, &frame->func_offset);
+      FillInMap(frame->pc, &frame->map);
+      num_frames++;
+    } else {
+      num_ignore_frames--;
+    }
+    ret = unw_step(&cursor);
+  } while (ret > 0 && num_frames < MAX_BACKTRACE_FRAMES);
+
+  unw_destroy_addr_space(addr_space);
+  context_ = nullptr;
+  return true;
+}
+
+bool BacktraceOffline::ReadWord(uintptr_t ptr, word_t* out_value) {
+  size_t bytes_read = Read(ptr, reinterpret_cast<uint8_t*>(out_value), sizeof(word_t));
+  return bytes_read == sizeof(word_t);
+}
+
+size_t BacktraceOffline::Read(uintptr_t addr, uint8_t* buffer, size_t bytes) {
+  // Normally, libunwind needs stack information and call frame information to do remote unwinding.
+  // If call frame information is stored in .debug_frame, libunwind can read it from file
+  // by itself. If call frame information is stored in .eh_frame, we need to provide data in
+  // .eh_frame/.eh_frame_hdr sections.
+  // The order of readings below doesn't matter, as the spaces don't overlap with each other.
+  size_t read_size = eh_frame_hdr_space_.Read(addr, buffer, bytes);
+  if (read_size != 0) {
+    return read_size;
+  }
+  read_size = eh_frame_space_.Read(addr, buffer, bytes);
+  if (read_size != 0) {
+    return read_size;
+  }
+  read_size = stack_space_.Read(addr, buffer, bytes);
+  return read_size;
+}
+
+static bool FileOffsetToVaddr(
+    const std::vector<DebugFrameInfo::EhFrame::ProgramHeader>& program_headers,
+    uint64_t file_offset, uint64_t* vaddr) {
+  for (auto& header : program_headers) {
+    if (file_offset >= header.file_offset && file_offset < header.file_offset + header.file_size) {
+      // TODO: Consider load_bias?
+      *vaddr = file_offset - header.file_offset + header.vaddr;
+      return true;
+    }
+  }
+  return false;
+}
+
+bool BacktraceOffline::FindProcInfo(unw_addr_space_t addr_space, uint64_t ip,
+                                    unw_proc_info_t* proc_info, int need_unwind_info) {
+  backtrace_map_t map;
+  FillInMap(ip, &map);
+  if (!BacktraceMap::IsValid(map)) {
+    return false;
+  }
+  const std::string& filename = map.name;
+  DebugFrameInfo* debug_frame = GetDebugFrameInFile(filename);
+  if (debug_frame == nullptr) {
+    return false;
+  }
+  if (debug_frame->is_eh_frame) {
+    uint64_t ip_offset = ip - map.start + map.offset;
+    uint64_t ip_vaddr;  // vaddr in the elf file.
+    bool result = FileOffsetToVaddr(debug_frame->eh_frame.program_headers, ip_offset, &ip_vaddr);
+    if (!result) {
+      return false;
+    }
+    // Calculate the addresses where .eh_frame_hdr and .eh_frame stay when the process was running.
+    eh_frame_hdr_space_.start = (ip - ip_vaddr) + debug_frame->eh_frame.eh_frame_hdr_vaddr;
+    eh_frame_hdr_space_.end =
+        eh_frame_hdr_space_.start + debug_frame->eh_frame.eh_frame_hdr_data.size();
+    eh_frame_hdr_space_.data = debug_frame->eh_frame.eh_frame_hdr_data.data();
+
+    eh_frame_space_.start = (ip - ip_vaddr) + debug_frame->eh_frame.eh_frame_vaddr;
+    eh_frame_space_.end = eh_frame_space_.start + debug_frame->eh_frame.eh_frame_data.size();
+    eh_frame_space_.data = debug_frame->eh_frame.eh_frame_data.data();
+
+    unw_dyn_info di;
+    memset(&di, '\0', sizeof(di));
+    di.start_ip = map.start;
+    di.end_ip = map.end;
+    di.format = UNW_INFO_FORMAT_REMOTE_TABLE;
+    di.u.rti.name_ptr = 0;
+    di.u.rti.segbase = eh_frame_hdr_space_.start;
+    di.u.rti.table_data =
+        eh_frame_hdr_space_.start + debug_frame->eh_frame.fde_table_offset_in_eh_frame_hdr;
+    di.u.rti.table_len = (eh_frame_hdr_space_.end - di.u.rti.table_data) / sizeof(unw_word_t);
+    int ret = dwarf_search_unwind_table(addr_space, ip, &di, proc_info, need_unwind_info, this);
+    return ret == 0;
+  }
+
+  eh_frame_hdr_space_.Clear();
+  eh_frame_space_.Clear();
+  unw_dyn_info_t di;
+  unw_word_t segbase = map.start - map.offset;
+  int found = dwarf_find_debug_frame(0, &di, ip, segbase, filename.c_str(), map.start, map.end);
+  if (found == 1) {
+    int ret = dwarf_search_unwind_table(addr_space, ip, &di, proc_info, need_unwind_info, this);
+    return ret == 0;
+  }
+  return false;
+}
+
+bool BacktraceOffline::ReadReg(size_t reg, uint64_t* value) {
+  bool result = true;
+#if defined(__arm__)
+  switch (reg) {
+    case UNW_ARM_R0:
+      *value = context_->uc_mcontext.arm_r0;
+      break;
+    case UNW_ARM_R1:
+      *value = context_->uc_mcontext.arm_r1;
+      break;
+    case UNW_ARM_R2:
+      *value = context_->uc_mcontext.arm_r2;
+      break;
+    case UNW_ARM_R3:
+      *value = context_->uc_mcontext.arm_r3;
+      break;
+    case UNW_ARM_R4:
+      *value = context_->uc_mcontext.arm_r4;
+      break;
+    case UNW_ARM_R5:
+      *value = context_->uc_mcontext.arm_r5;
+      break;
+    case UNW_ARM_R6:
+      *value = context_->uc_mcontext.arm_r6;
+      break;
+    case UNW_ARM_R7:
+      *value = context_->uc_mcontext.arm_r7;
+      break;
+    case UNW_ARM_R8:
+      *value = context_->uc_mcontext.arm_r8;
+      break;
+    case UNW_ARM_R9:
+      *value = context_->uc_mcontext.arm_r9;
+      break;
+    case UNW_ARM_R10:
+      *value = context_->uc_mcontext.arm_r10;
+      break;
+    case UNW_ARM_R11:
+      *value = context_->uc_mcontext.arm_fp;
+      break;
+    case UNW_ARM_R12:
+      *value = context_->uc_mcontext.arm_ip;
+      break;
+    case UNW_ARM_R13:
+      *value = context_->uc_mcontext.arm_sp;
+      break;
+    case UNW_ARM_R14:
+      *value = context_->uc_mcontext.arm_lr;
+      break;
+    case UNW_ARM_R15:
+      *value = context_->uc_mcontext.arm_pc;
+      break;
+    default:
+      result = false;
+  }
+#elif defined(__aarch64__)
+  if (reg <= UNW_AARCH64_PC) {
+    *value = context_->uc_mcontext.regs[reg];
+  } else {
+    result = false;
+  }
+#elif defined(__x86_64__)
+  switch (reg) {
+    case UNW_X86_64_R8:
+      *value = context_->uc_mcontext.gregs[REG_R8];
+      break;
+    case UNW_X86_64_R9:
+      *value = context_->uc_mcontext.gregs[REG_R9];
+      break;
+    case UNW_X86_64_R10:
+      *value = context_->uc_mcontext.gregs[REG_R10];
+      break;
+    case UNW_X86_64_R11:
+      *value = context_->uc_mcontext.gregs[REG_R11];
+      break;
+    case UNW_X86_64_R12:
+      *value = context_->uc_mcontext.gregs[REG_R12];
+      break;
+    case UNW_X86_64_R13:
+      *value = context_->uc_mcontext.gregs[REG_R13];
+      break;
+    case UNW_X86_64_R14:
+      *value = context_->uc_mcontext.gregs[REG_R14];
+      break;
+    case UNW_X86_64_R15:
+      *value = context_->uc_mcontext.gregs[REG_R15];
+      break;
+    case UNW_X86_64_RDI:
+      *value = context_->uc_mcontext.gregs[REG_RDI];
+      break;
+    case UNW_X86_64_RSI:
+      *value = context_->uc_mcontext.gregs[REG_RSI];
+      break;
+    case UNW_X86_64_RBP:
+      *value = context_->uc_mcontext.gregs[REG_RBP];
+      break;
+    case UNW_X86_64_RBX:
+      *value = context_->uc_mcontext.gregs[REG_RBX];
+      break;
+    case UNW_X86_64_RDX:
+      *value = context_->uc_mcontext.gregs[REG_RDX];
+      break;
+    case UNW_X86_64_RAX:
+      *value = context_->uc_mcontext.gregs[REG_RAX];
+      break;
+    case UNW_X86_64_RCX:
+      *value = context_->uc_mcontext.gregs[REG_RCX];
+      break;
+    case UNW_X86_64_RSP:
+      *value = context_->uc_mcontext.gregs[REG_RSP];
+      break;
+    case UNW_X86_64_RIP:
+      *value = context_->uc_mcontext.gregs[REG_RIP];
+      break;
+    default:
+      result = false;
+  }
+#elif defined(__i386__)
+  switch (reg) {
+    case UNW_X86_GS:
+      *value = context_->uc_mcontext.gregs[REG_GS];
+      break;
+    case UNW_X86_FS:
+      *value = context_->uc_mcontext.gregs[REG_FS];
+      break;
+    case UNW_X86_ES:
+      *value = context_->uc_mcontext.gregs[REG_ES];
+      break;
+    case UNW_X86_DS:
+      *value = context_->uc_mcontext.gregs[REG_DS];
+      break;
+    case UNW_X86_EAX:
+      *value = context_->uc_mcontext.gregs[REG_EAX];
+      break;
+    case UNW_X86_EBX:
+      *value = context_->uc_mcontext.gregs[REG_EBX];
+      break;
+    case UNW_X86_ECX:
+      *value = context_->uc_mcontext.gregs[REG_ECX];
+      break;
+    case UNW_X86_EDX:
+      *value = context_->uc_mcontext.gregs[REG_EDX];
+      break;
+    case UNW_X86_ESI:
+      *value = context_->uc_mcontext.gregs[REG_ESI];
+      break;
+    case UNW_X86_EDI:
+      *value = context_->uc_mcontext.gregs[REG_EDI];
+      break;
+    case UNW_X86_EBP:
+      *value = context_->uc_mcontext.gregs[REG_EBP];
+      break;
+    case UNW_X86_EIP:
+      *value = context_->uc_mcontext.gregs[REG_EIP];
+      break;
+    case UNW_X86_ESP:
+      *value = context_->uc_mcontext.gregs[REG_ESP];
+      break;
+    case UNW_X86_TRAPNO:
+      *value = context_->uc_mcontext.gregs[REG_TRAPNO];
+      break;
+    case UNW_X86_CS:
+      *value = context_->uc_mcontext.gregs[REG_CS];
+      break;
+    case UNW_X86_EFLAGS:
+      *value = context_->uc_mcontext.gregs[REG_EFL];
+      break;
+    case UNW_X86_SS:
+      *value = context_->uc_mcontext.gregs[REG_SS];
+      break;
+    default:
+      result = false;
+  }
+#endif
+  return result;
+}
+
+std::string BacktraceOffline::GetFunctionNameRaw(uintptr_t, uintptr_t* offset) {
+  // We don't have enough information to support this. And it is expensive.
+  *offset = 0;
+  return "";
+}
+
+std::unordered_map<std::string, std::unique_ptr<DebugFrameInfo>> BacktraceOffline::debug_frames_;
+std::unordered_set<std::string> BacktraceOffline::debug_frame_missing_files_;
+
+static DebugFrameInfo* ReadDebugFrameFromFile(const std::string& filename);
+
+DebugFrameInfo* BacktraceOffline::GetDebugFrameInFile(const std::string& filename) {
+  if (cache_file_) {
+    auto it = debug_frames_.find(filename);
+    if (it != debug_frames_.end()) {
+      return it->second.get();
+    }
+    if (debug_frame_missing_files_.find(filename) != debug_frame_missing_files_.end()) {
+      return nullptr;
+    }
+  }
+  DebugFrameInfo* debug_frame = ReadDebugFrameFromFile(filename);
+  if (cache_file_) {
+    if (debug_frame != nullptr) {
+      debug_frames_.emplace(filename, std::unique_ptr<DebugFrameInfo>(debug_frame));
+    } else {
+      debug_frame_missing_files_.insert(filename);
+    }
+  } else {
+    if (last_debug_frame_ != nullptr) {
+      delete last_debug_frame_;
+    }
+    last_debug_frame_ = debug_frame;
+  }
+  return debug_frame;
+}
+
+static bool OmitEncodedValue(uint8_t encode, const uint8_t*& p) {
+  if (encode == DW_EH_PE_omit) {
+    return 0;
+  }
+  uint8_t format = encode & 0x0f;
+  switch (format) {
+    case DW_EH_PE_ptr:
+      p += sizeof(unw_word_t);
+      break;
+    case DW_EH_PE_uleb128:
+    case DW_EH_PE_sleb128:
+      while ((*p & 0x80) != 0) {
+        ++p;
+      }
+      ++p;
+      break;
+    case DW_EH_PE_udata2:
+    case DW_EH_PE_sdata2:
+      p += 2;
+      break;
+    case DW_EH_PE_udata4:
+    case DW_EH_PE_sdata4:
+      p += 4;
+      break;
+    case DW_EH_PE_udata8:
+    case DW_EH_PE_sdata8:
+      p += 8;
+      break;
+    default:
+      return false;
+  }
+  return true;
+}
+
+static bool GetFdeTableOffsetInEhFrameHdr(const std::vector<uint8_t>& data,
+                                          uint64_t* table_offset_in_eh_frame_hdr) {
+  const uint8_t* p = data.data();
+  const uint8_t* end = p + data.size();
+  if (p + 4 > end) {
+    return false;
+  }
+  uint8_t version = *p++;
+  if (version != 1) {
+    return false;
+  }
+  uint8_t eh_frame_ptr_encode = *p++;
+  uint8_t fde_count_encode = *p++;
+  uint8_t fde_table_encode = *p++;
+
+  if (fde_table_encode != (DW_EH_PE_datarel | DW_EH_PE_sdata4)) {
+    return false;
+  }
+
+  if (!OmitEncodedValue(eh_frame_ptr_encode, p) || !OmitEncodedValue(fde_count_encode, p)) {
+    return false;
+  }
+  if (p >= end) {
+    return false;
+  }
+  *table_offset_in_eh_frame_hdr = p - data.data();
+  return true;
+}
+
+using ProgramHeader = DebugFrameInfo::EhFrame::ProgramHeader;
+
+template <class ELFT>
+DebugFrameInfo* ReadDebugFrameFromELFFile(const llvm::object::ELFFile<ELFT>* elf) {
+  bool has_eh_frame_hdr = false;
+  uint64_t eh_frame_hdr_vaddr = 0;
+  std::vector<uint8_t> eh_frame_hdr_data;
+  bool has_eh_frame = false;
+  uint64_t eh_frame_vaddr = 0;
+  std::vector<uint8_t> eh_frame_data;
+
+  for (auto it = elf->begin_sections(); it != elf->end_sections(); ++it) {
+    llvm::ErrorOr<llvm::StringRef> name = elf->getSectionName(&*it);
+    if (name) {
+      if (name.get() == ".debug_frame") {
+        DebugFrameInfo* debug_frame = new DebugFrameInfo;
+        debug_frame->is_eh_frame = false;
+        return debug_frame;
+      }
+      if (name.get() == ".eh_frame_hdr") {
+        has_eh_frame_hdr = true;
+        eh_frame_hdr_vaddr = it->sh_addr;
+        llvm::ErrorOr<llvm::ArrayRef<uint8_t>> data = elf->getSectionContents(&*it);
+        if (data) {
+          eh_frame_hdr_data.insert(eh_frame_hdr_data.begin(), data->data(),
+                                   data->data() + data->size());
+        } else {
+          return nullptr;
+        }
+      } else if (name.get() == ".eh_frame") {
+        has_eh_frame = true;
+        eh_frame_vaddr = it->sh_addr;
+        llvm::ErrorOr<llvm::ArrayRef<uint8_t>> data = elf->getSectionContents(&*it);
+        if (data) {
+          eh_frame_data.insert(eh_frame_data.begin(), data->data(), data->data() + data->size());
+        } else {
+          return nullptr;
+        }
+      }
+    }
+  }
+  if (!(has_eh_frame_hdr && has_eh_frame)) {
+    return nullptr;
+  }
+  uint64_t fde_table_offset;
+  if (!GetFdeTableOffsetInEhFrameHdr(eh_frame_hdr_data, &fde_table_offset)) {
+    return nullptr;
+  }
+
+  std::vector<ProgramHeader> program_headers;
+  for (auto it = elf->begin_program_headers(); it != elf->end_program_headers(); ++it) {
+    ProgramHeader header;
+    header.vaddr = it->p_vaddr;
+    header.file_offset = it->p_offset;
+    header.file_size = it->p_filesz;
+    program_headers.push_back(header);
+  }
+  DebugFrameInfo* debug_frame = new DebugFrameInfo;
+  debug_frame->is_eh_frame = true;
+  debug_frame->eh_frame.eh_frame_hdr_vaddr = eh_frame_hdr_vaddr;
+  debug_frame->eh_frame.eh_frame_vaddr = eh_frame_vaddr;
+  debug_frame->eh_frame.fde_table_offset_in_eh_frame_hdr = fde_table_offset;
+  debug_frame->eh_frame.eh_frame_hdr_data = std::move(eh_frame_hdr_data);
+  debug_frame->eh_frame.eh_frame_data = std::move(eh_frame_data);
+  debug_frame->eh_frame.program_headers = program_headers;
+  return debug_frame;
+}
+
+static DebugFrameInfo* ReadDebugFrameFromFile(const std::string& filename) {
+  auto owning_binary = llvm::object::createBinary(llvm::StringRef(filename));
+  if (owning_binary.getError()) {
+    return nullptr;
+  }
+  llvm::object::Binary* binary = owning_binary.get().getBinary();
+  auto obj = llvm::dyn_cast<llvm::object::ObjectFile>(binary);
+  if (obj == nullptr) {
+    return nullptr;
+  }
+  if (auto elf = llvm::dyn_cast<llvm::object::ELF32LEObjectFile>(obj)) {
+    return ReadDebugFrameFromELFFile(elf->getELFFile());
+  }
+  if (auto elf = llvm::dyn_cast<llvm::object::ELF64LEObjectFile>(obj)) {
+    return ReadDebugFrameFromELFFile(elf->getELFFile());
+  }
+  return nullptr;
+}
diff --git a/libbacktrace/BacktraceOffline.h b/libbacktrace/BacktraceOffline.h
new file mode 100644
index 0000000..42f826d
--- /dev/null
+++ b/libbacktrace/BacktraceOffline.h
@@ -0,0 +1,105 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef _LIBBACKTRACE_UNWIND_OFFLINE_H
+#define _LIBBACKTRACE_UNWIND_OFFLINE_H
+
+#include <libunwind.h>
+#include <stdint.h>
+#include <sys/types.h>
+#include <ucontext.h>
+
+#include <unordered_map>
+#include <unordered_set>
+
+#include <backtrace/Backtrace.h>
+
+struct Space {
+  uint64_t start;
+  uint64_t end;
+  const uint8_t* data;
+
+  Space() {
+    Clear();
+  }
+
+  void Clear();
+  size_t Read(uint64_t addr, uint8_t* buffer, size_t size);
+};
+
+struct DebugFrameInfo {
+  bool is_eh_frame;
+  struct EhFrame {
+    uint64_t eh_frame_hdr_vaddr;
+    uint64_t eh_frame_vaddr;
+    uint64_t fde_table_offset_in_eh_frame_hdr;
+    std::vector<uint8_t> eh_frame_hdr_data;
+    std::vector<uint8_t> eh_frame_data;
+    struct ProgramHeader {
+      uint64_t vaddr;
+      uint64_t file_offset;
+      uint64_t file_size;
+    };
+    std::vector<ProgramHeader> program_headers;
+  } eh_frame;
+};
+
+class BacktraceOffline : public Backtrace {
+ public:
+  BacktraceOffline(pid_t pid, pid_t tid, BacktraceMap* map, const backtrace_stackinfo_t& stack,
+                   bool cache_file)
+      : Backtrace(pid, tid, map),
+        cache_file_(cache_file),
+        context_(nullptr),
+        last_debug_frame_(nullptr) {
+    stack_space_.start = stack.start;
+    stack_space_.end = stack.end;
+    stack_space_.data = stack.data;
+  }
+
+  virtual ~BacktraceOffline() {
+    if (last_debug_frame_ != nullptr) {
+      delete last_debug_frame_;
+    }
+  }
+
+  bool Unwind(size_t num_ignore_frames, ucontext_t* context) override;
+
+  bool ReadWord(uintptr_t ptr, word_t* out_value) override;
+
+  size_t Read(uintptr_t addr, uint8_t* buffer, size_t bytes) override;
+
+  bool FindProcInfo(unw_addr_space_t addr_space, uint64_t ip, unw_proc_info_t* proc_info,
+                    int need_unwind_info);
+
+  bool ReadReg(size_t reg_index, uint64_t* value);
+
+ protected:
+  std::string GetFunctionNameRaw(uintptr_t pc, uintptr_t* offset) override;
+  DebugFrameInfo* GetDebugFrameInFile(const std::string& filename);
+
+  static std::unordered_map<std::string, std::unique_ptr<DebugFrameInfo>> debug_frames_;
+  static std::unordered_set<std::string> debug_frame_missing_files_;
+
+  bool cache_file_;
+  ucontext_t* context_;
+  Space eh_frame_hdr_space_;
+  Space eh_frame_space_;
+  Space stack_space_;
+  DebugFrameInfo* last_debug_frame_;
+};
+
+#endif  // _LIBBACKTRACE_BACKTRACE_OFFLINE_H
diff --git a/libbacktrace/backtrace_offline_test.cpp b/libbacktrace/backtrace_offline_test.cpp
new file mode 100644
index 0000000..88a3533
--- /dev/null
+++ b/libbacktrace/backtrace_offline_test.cpp
@@ -0,0 +1,189 @@
+#include <libunwind.h>
+#include <pthread.h>
+#include <stdint.h>
+#include <string.h>
+
+#include <functional>
+#include <memory>
+#include <string>
+#include <utility>
+#include <vector>
+
+#include <backtrace/Backtrace.h>
+#include <backtrace/BacktraceMap.h>
+#include <cutils/threads.h>
+
+#include <gtest/gtest.h>
+
+extern "C" {
+// Prototypes for functions in the test library.
+int test_level_one(int, int, int, int, void (*)(void*), void*);
+int test_level_two(int, int, int, int, void (*)(void*), void*);
+int test_level_three(int, int, int, int, void (*)(void*), void*);
+int test_level_four(int, int, int, int, void (*)(void*), void*);
+int test_recursive_call(int, void (*)(void*), void*);
+}
+
+static volatile bool g_exit_flag = false;
+
+static void GetContextAndExit(void* arg) {
+  unw_context_t* unw_context = reinterpret_cast<unw_context_t*>(arg);
+  unw_getcontext(unw_context);
+  // Don't touch the stack anymore.
+  while (!g_exit_flag) {
+  }
+}
+
+struct OfflineThreadArg {
+  unw_context_t unw_context;
+  pid_t tid;
+  std::function<int(void (*)(void*), void*)> function;
+};
+
+static void* OfflineThreadFunc(void* arg) {
+  OfflineThreadArg* fn_arg = reinterpret_cast<OfflineThreadArg*>(arg);
+  fn_arg->tid = gettid();
+  fn_arg->function(GetContextAndExit, &fn_arg->unw_context);
+  return nullptr;
+}
+
+static ucontext_t GetUContextFromUnwContext(const unw_context_t& unw_context) {
+  ucontext_t ucontext;
+  memset(&ucontext, 0, sizeof(ucontext));
+#if defined(__arm__)
+  ucontext.uc_mcontext.arm_r0 = unw_context.regs[0];
+  ucontext.uc_mcontext.arm_r1 = unw_context.regs[1];
+  ucontext.uc_mcontext.arm_r2 = unw_context.regs[2];
+  ucontext.uc_mcontext.arm_r3 = unw_context.regs[3];
+  ucontext.uc_mcontext.arm_r4 = unw_context.regs[4];
+  ucontext.uc_mcontext.arm_r5 = unw_context.regs[5];
+  ucontext.uc_mcontext.arm_r6 = unw_context.regs[6];
+  ucontext.uc_mcontext.arm_r7 = unw_context.regs[7];
+  ucontext.uc_mcontext.arm_r8 = unw_context.regs[8];
+  ucontext.uc_mcontext.arm_r9 = unw_context.regs[9];
+  ucontext.uc_mcontext.arm_r10 = unw_context.regs[10];
+  ucontext.uc_mcontext.arm_fp = unw_context.regs[11];
+  ucontext.uc_mcontext.arm_ip = unw_context.regs[12];
+  ucontext.uc_mcontext.arm_sp = unw_context.regs[13];
+  ucontext.uc_mcontext.arm_lr = unw_context.regs[14];
+  ucontext.uc_mcontext.arm_pc = unw_context.regs[15];
+#else
+  ucontext.uc_mcontext = unw_context.uc_mcontext;
+#endif
+  return ucontext;
+}
+
+static void OfflineBacktraceFunctionCall(std::function<int(void (*)(void*), void*)> function,
+                                         std::vector<uintptr_t>* pc_values) {
+  // Create a thread to generate the needed stack and registers information.
+  g_exit_flag = false;
+  const size_t stack_size = 1024 * 1024;
+  void* stack = mmap(NULL, stack_size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+  ASSERT_NE(MAP_FAILED, stack);
+  uintptr_t stack_addr = reinterpret_cast<uintptr_t>(stack);
+  pthread_attr_t attr;
+  ASSERT_EQ(0, pthread_attr_init(&attr));
+  ASSERT_EQ(0, pthread_attr_setstack(&attr, reinterpret_cast<void*>(stack), stack_size));
+  pthread_t thread;
+  OfflineThreadArg arg;
+  arg.function = function;
+  ASSERT_EQ(0, pthread_create(&thread, &attr, OfflineThreadFunc, &arg));
+  // Wait for the offline thread to generate the stack and unw_context information.
+  sleep(1);
+  // Copy the stack information.
+  std::vector<uint8_t> stack_data(reinterpret_cast<uint8_t*>(stack),
+                                  reinterpret_cast<uint8_t*>(stack) + stack_size);
+  g_exit_flag = true;
+  ASSERT_EQ(0, pthread_join(thread, nullptr));
+  ASSERT_EQ(0, munmap(stack, stack_size));
+
+  // Do offline backtrace.
+  std::unique_ptr<BacktraceMap> map(BacktraceMap::Create(getpid()));
+  ASSERT_TRUE(map != nullptr);
+
+  backtrace_stackinfo_t stack_info;
+  stack_info.start = stack_addr;
+  stack_info.end = stack_addr + stack_size;
+  stack_info.data = stack_data.data();
+
+  std::unique_ptr<Backtrace> backtrace(
+      Backtrace::CreateOffline(getpid(), arg.tid, map.get(), stack_info));
+  ASSERT_TRUE(backtrace != nullptr);
+
+  ucontext_t ucontext = GetUContextFromUnwContext(arg.unw_context);
+  ASSERT_TRUE(backtrace->Unwind(0, &ucontext));
+
+  // Collect pc values of the call stack frames.
+  for (size_t i = 0; i < backtrace->NumFrames(); ++i) {
+    pc_values->push_back(backtrace->GetFrame(i)->pc);
+  }
+}
+
+// Return the name of the function which matches the address. Although we don't know the
+// exact end of each function, it is accurate enough for the tests.
+static std::string FunctionNameForAddress(uintptr_t addr) {
+  struct FunctionSymbol {
+    std::string name;
+    uintptr_t start;
+    uintptr_t end;
+  };
+
+  static std::vector<FunctionSymbol> symbols;
+  if (symbols.empty()) {
+    symbols = std::vector<FunctionSymbol>{
+        {"unknown_start", 0, 0},
+        {"test_level_one", reinterpret_cast<uintptr_t>(&test_level_one), 0},
+        {"test_level_two", reinterpret_cast<uintptr_t>(&test_level_two), 0},
+        {"test_level_three", reinterpret_cast<uintptr_t>(&test_level_three), 0},
+        {"test_level_four", reinterpret_cast<uintptr_t>(&test_level_four), 0},
+        {"test_recursive_call", reinterpret_cast<uintptr_t>(&test_recursive_call), 0},
+        {"GetContextAndExit", reinterpret_cast<uintptr_t>(&GetContextAndExit), 0},
+        {"unknown_end", static_cast<uintptr_t>(-1), static_cast<uintptr_t>(-1)},
+    };
+    std::sort(
+        symbols.begin(), symbols.end(),
+        [](const FunctionSymbol& s1, const FunctionSymbol& s2) { return s1.start < s2.start; });
+    for (size_t i = 0; i + 1 < symbols.size(); ++i) {
+      symbols[i].end = symbols[i + 1].start;
+    }
+  }
+  for (auto& symbol : symbols) {
+    if (addr >= symbol.start && addr < symbol.end) {
+      return symbol.name;
+    }
+  }
+  return "";
+}
+
+TEST(libbacktrace, offline) {
+  std::function<int(void (*)(void*), void*)> function =
+      std::bind(test_level_one, 1, 2, 3, 4, std::placeholders::_1, std::placeholders::_2);
+  std::vector<uintptr_t> pc_values;
+  OfflineBacktraceFunctionCall(function, &pc_values);
+  ASSERT_FALSE(pc_values.empty());
+  ASSERT_LE(pc_values.size(), static_cast<size_t>(MAX_BACKTRACE_FRAMES));
+
+  size_t test_one_index = 0;
+  for (size_t i = 0; i < pc_values.size(); ++i) {
+    if (FunctionNameForAddress(pc_values[i]) == "test_level_one") {
+      test_one_index = i;
+      break;
+    }
+  }
+
+  ASSERT_GE(test_one_index, 3u);
+  ASSERT_EQ("test_level_one", FunctionNameForAddress(pc_values[test_one_index]));
+  ASSERT_EQ("test_level_two", FunctionNameForAddress(pc_values[test_one_index - 1]));
+  ASSERT_EQ("test_level_three", FunctionNameForAddress(pc_values[test_one_index - 2]));
+  ASSERT_EQ("test_level_four", FunctionNameForAddress(pc_values[test_one_index - 3]));
+}
+
+TEST(libbacktrace, offline_max_trace) {
+  std::function<int(void (*)(void*), void*)> function = std::bind(
+      test_recursive_call, MAX_BACKTRACE_FRAMES + 10, std::placeholders::_1, std::placeholders::_2);
+  std::vector<uintptr_t> pc_values;
+  OfflineBacktraceFunctionCall(function, &pc_values);
+  ASSERT_FALSE(pc_values.empty());
+  ASSERT_EQ(static_cast<size_t>(MAX_BACKTRACE_FRAMES), pc_values.size());
+  ASSERT_EQ("test_recursive_call", FunctionNameForAddress(pc_values.back()));
+}
diff --git a/logcat/Android.mk b/logcat/Android.mk
index 844ab8b..c4a9550 100644
--- a/logcat/Android.mk
+++ b/logcat/Android.mk
@@ -15,4 +15,15 @@
 
 include $(BUILD_EXECUTABLE)
 
+include $(CLEAR_VARS)
+
+LOCAL_MODULE := logpersist.start
+LOCAL_MODULE_TAGS := debug
+LOCAL_MODULE_CLASS := EXECUTABLES
+LOCAL_MODULE_PATH := $(bin_dir)
+LOCAL_SRC_FILES := logpersist
+ALL_TOOLS := logpersist.start logpersist.stop logpersist.cat
+LOCAL_POST_INSTALL_CMD := $(hide) $(foreach t,$(filter-out $(LOCAL_MODULE),$(ALL_TOOLS)),ln -sf $(LOCAL_MODULE) $(TARGET_OUT)/bin/$(t);)
+include $(BUILD_PREBUILT)
+
 include $(call first-makefiles-under,$(LOCAL_PATH))
diff --git a/logcat/logcatd.rc b/logcat/logcatd.rc
index 0bc581e..33d39ac 100644
--- a/logcat/logcatd.rc
+++ b/logcat/logcatd.rc
@@ -2,10 +2,10 @@
     # all exec/services are called with umask(077), so no gain beyond 0700
     mkdir /data/misc/logd 0700 logd log
     # logd for write to /data/misc/logd, log group for read from pstore (-L)
-    exec - logd log -- /system/bin/logcat -L -b all -v threadtime -v usec -v printable -D -f /data/misc/logd/logcat -r 64 -n 256
+    exec - logd log -- /system/bin/logcat -L -b all -v threadtime -v usec -v printable -D -f /data/misc/logd/logcat -r 1024 -n 256
     start logcatd
 
-service logcatd /system/bin/logcat -b all -v threadtime -v usec -v printable -D -f /data/misc/logd/logcat -r 64 -n 256
+service logcatd /system/bin/logcat -b all -v threadtime -v usec -v printable -D -f /data/misc/logd/logcat -r 1024 -n 256
     class late_start
     disabled
     # logd for write to /data/misc/logd, log group for read from log daemon
diff --git a/logd/logpersist b/logcat/logpersist
similarity index 88%
rename from logd/logpersist
rename to logcat/logpersist
index 215e1e2..6f666f6 100755
--- a/logd/logpersist
+++ b/logcat/logpersist
@@ -1,9 +1,15 @@
 #! /system/bin/sh
 # logpersist cat start and stop handlers
+progname="${0##*/}"
+case `getprop ro.build.type` in
+userdebug|eng) ;;
+*) echo "${progname} - Permission denied"
+   exit 1
+   ;;
+esac
 data=/data/misc/logd
 property=persist.logd.logpersistd
 service=logcatd
-progname="${0##*/}"
 if [ X"${1}" = "-h" -o X"${1}" = X"--help" ]; then
   echo "${progname%.*}.cat            - dump current ${service%d} logs"
   echo "${progname%.*}.start          - start ${service} service"
diff --git a/logd/Android.mk b/logd/Android.mk
index 01c51c7..c00061b 100644
--- a/logd/Android.mk
+++ b/logd/Android.mk
@@ -43,15 +43,4 @@
 
 include $(BUILD_EXECUTABLE)
 
-include $(CLEAR_VARS)
-
-LOCAL_MODULE := logpersist.start
-LOCAL_MODULE_TAGS := debug
-LOCAL_MODULE_CLASS := EXECUTABLES
-LOCAL_MODULE_PATH := $(bin_dir)
-LOCAL_SRC_FILES := logpersist
-ALL_TOOLS := logpersist.start logpersist.stop logpersist.cat
-LOCAL_POST_INSTALL_CMD := $(hide) $(foreach t,$(filter-out $(LOCAL_MODULE),$(ALL_TOOLS)),ln -sf $(LOCAL_MODULE) $(TARGET_OUT)/bin/$(t);)
-include $(BUILD_PREBUILT)
-
 include $(call first-makefiles-under,$(LOCAL_PATH))
diff --git a/metricsd/metrics_daemon_test.cc b/metricsd/metrics_daemon_test.cc
index 476d0f3..1adf9de 100644
--- a/metricsd/metrics_daemon_test.cc
+++ b/metricsd/metrics_daemon_test.cc
@@ -25,6 +25,7 @@
 #include <base/files/scoped_temp_dir.h>
 #include <base/strings/string_number_conversions.h>
 #include <base/strings/stringprintf.h>
+#include <chromeos/flag_helper.h>
 #include <gtest/gtest.h>
 
 #include "constants.h"
@@ -60,6 +61,7 @@
   std::string kFakeDiskStats1;
 
   virtual void SetUp() {
+    chromeos::FlagHelper::Init(0, nullptr, "");
     EXPECT_TRUE(temp_dir_.CreateUniqueTempDir());
     scaling_max_freq_path_ = temp_dir_.path().Append("scaling_max");
     cpu_max_freq_path_ = temp_dir_.path().Append("cpu_freq_max");