diff --git a/src/log-utils.cc b/src/log-utils.cc
index 7bd7baa..c94d07a 100644
--- a/src/log-utils.cc
+++ b/src/log-utils.cc
@@ -1,172 +1,73 @@
 // Copyright 2009 the V8 project authors. 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.
-//     * Neither the name of Google Inc. nor the names of its
-//       contributors may be used to endorse or promote products derived
-//       from this software without specific prior written permission.
-//
-// 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.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
 
-#include "v8.h"
+#include "src/v8.h"
 
-#include "log-utils.h"
-#include "string-stream.h"
+#include "src/log-utils.h"
+#include "src/string-stream.h"
 
 namespace v8 {
 namespace internal {
 
 
 const char* const Log::kLogToTemporaryFile = "&";
+const char* const Log::kLogToConsole = "-";
 
 
 Log::Log(Logger* logger)
   : is_stopped_(false),
     output_handle_(NULL),
-    ll_output_handle_(NULL),
-    mutex_(NULL),
     message_buffer_(NULL),
     logger_(logger) {
 }
 
 
-static void AddIsolateIdIfNeeded(StringStream* stream) {
-  Isolate* isolate = Isolate::Current();
-  if (isolate->IsDefaultIsolate()) return;
-  stream->Add("isolate-%p-", isolate);
-}
-
-
-void Log::Initialize() {
-  mutex_ = OS::CreateMutex();
+void Log::Initialize(const char* log_file_name) {
   message_buffer_ = NewArray<char>(kMessageBufferSize);
 
   // --log-all enables all the log flags.
   if (FLAG_log_all) {
-    FLAG_log_runtime = true;
     FLAG_log_api = true;
     FLAG_log_code = true;
     FLAG_log_gc = true;
     FLAG_log_suspect = true;
     FLAG_log_handles = true;
     FLAG_log_regexp = true;
+    FLAG_log_internal_timer_events = true;
   }
 
   // --prof implies --log-code.
   if (FLAG_prof) FLAG_log_code = true;
 
-  // --prof_lazy controls --log-code, implies --noprof_auto.
-  if (FLAG_prof_lazy) {
-    FLAG_log_code = false;
-    FLAG_prof_auto = false;
-  }
-
-  bool open_log_file = FLAG_log || FLAG_log_runtime || FLAG_log_api
-      || FLAG_log_code || FLAG_log_gc || FLAG_log_handles || FLAG_log_suspect
-      || FLAG_log_regexp || FLAG_log_state_changes || FLAG_ll_prof;
-
   // If we're logging anything, we need to open the log file.
-  if (open_log_file) {
-    if (strcmp(FLAG_logfile, "-") == 0) {
+  if (Log::InitLogAtStart()) {
+    if (strcmp(log_file_name, kLogToConsole) == 0) {
       OpenStdout();
-    } else if (strcmp(FLAG_logfile, kLogToTemporaryFile) == 0) {
+    } else if (strcmp(log_file_name, kLogToTemporaryFile) == 0) {
       OpenTemporaryFile();
     } else {
-      if (strchr(FLAG_logfile, '%') != NULL ||
-          !Isolate::Current()->IsDefaultIsolate()) {
-        // If there's a '%' in the log file name we have to expand
-        // placeholders.
-        HeapStringAllocator allocator;
-        StringStream stream(&allocator);
-        AddIsolateIdIfNeeded(&stream);
-        for (const char* p = FLAG_logfile; *p; p++) {
-          if (*p == '%') {
-            p++;
-            switch (*p) {
-              case '\0':
-                // If there's a % at the end of the string we back up
-                // one character so we can escape the loop properly.
-                p--;
-                break;
-              case 't': {
-                // %t expands to the current time in milliseconds.
-                double time = OS::TimeCurrentMillis();
-                stream.Add("%.0f", FmtElm(time));
-                break;
-              }
-              case '%':
-                // %% expands (contracts really) to %.
-                stream.Put('%');
-                break;
-              default:
-                // All other %'s expand to themselves.
-                stream.Put('%');
-                stream.Put(*p);
-                break;
-            }
-          } else {
-            stream.Put(*p);
-          }
-        }
-        SmartArrayPointer<const char> expanded = stream.ToCString();
-        OpenFile(*expanded);
-      } else {
-        OpenFile(FLAG_logfile);
-      }
+      OpenFile(log_file_name);
     }
   }
 }
 
 
 void Log::OpenStdout() {
-  ASSERT(!IsEnabled());
+  DCHECK(!IsEnabled());
   output_handle_ = stdout;
 }
 
 
 void Log::OpenTemporaryFile() {
-  ASSERT(!IsEnabled());
-  output_handle_ = i::OS::OpenTemporaryFile();
+  DCHECK(!IsEnabled());
+  output_handle_ = base::OS::OpenTemporaryFile();
 }
 
 
-// Extension added to V8 log file name to get the low-level log name.
-static const char kLowLevelLogExt[] = ".ll";
-
-// File buffer size of the low-level log. We don't use the default to
-// minimize the associated overhead.
-static const int kLowLevelLogBufferSize = 2 * MB;
-
-
 void Log::OpenFile(const char* name) {
-  ASSERT(!IsEnabled());
-  output_handle_ = OS::FOpen(name, OS::LogFileOpenMode);
-  if (FLAG_ll_prof) {
-    // Open the low-level log file.
-    size_t len = strlen(name);
-    ScopedVector<char> ll_name(static_cast<int>(len + sizeof(kLowLevelLogExt)));
-    memcpy(ll_name.start(), name, len);
-    memcpy(ll_name.start() + len, kLowLevelLogExt, sizeof(kLowLevelLogExt));
-    ll_output_handle_ = OS::FOpen(ll_name.start(), OS::LogFileOpenMode);
-    setvbuf(ll_output_handle_, NULL, _IOFBF, kLowLevelLogBufferSize);
-  }
+  DCHECK(!IsEnabled());
+  output_handle_ = base::OS::FOpen(name, base::OS::LogFileOpenMode);
 }
 
 
@@ -180,43 +81,38 @@
     }
   }
   output_handle_ = NULL;
-  if (ll_output_handle_ != NULL) fclose(ll_output_handle_);
-  ll_output_handle_ = NULL;
 
   DeleteArray(message_buffer_);
   message_buffer_ = NULL;
 
-  delete mutex_;
-  mutex_ = NULL;
-
   is_stopped_ = false;
   return result;
 }
 
 
-LogMessageBuilder::LogMessageBuilder(Logger* logger)
-  : log_(logger->log_),
-    sl(log_->mutex_),
+Log::MessageBuilder::MessageBuilder(Log* log)
+  : log_(log),
+    lock_guard_(&log_->mutex_),
     pos_(0) {
-  ASSERT(log_->message_buffer_ != NULL);
+  DCHECK(log_->message_buffer_ != NULL);
 }
 
 
-void LogMessageBuilder::Append(const char* format, ...) {
+void Log::MessageBuilder::Append(const char* format, ...) {
   Vector<char> buf(log_->message_buffer_ + pos_,
                    Log::kMessageBufferSize - pos_);
   va_list args;
   va_start(args, format);
   AppendVA(format, args);
   va_end(args);
-  ASSERT(pos_ <= Log::kMessageBufferSize);
+  DCHECK(pos_ <= Log::kMessageBufferSize);
 }
 
 
-void LogMessageBuilder::AppendVA(const char* format, va_list args) {
+void Log::MessageBuilder::AppendVA(const char* format, va_list args) {
   Vector<char> buf(log_->message_buffer_ + pos_,
                    Log::kMessageBufferSize - pos_);
-  int result = v8::internal::OS::VSNPrintF(buf, format, args);
+  int result = v8::internal::VSNPrintF(buf, format, args);
 
   // Result is -1 if output was truncated.
   if (result >= 0) {
@@ -224,20 +120,32 @@
   } else {
     pos_ = Log::kMessageBufferSize;
   }
-  ASSERT(pos_ <= Log::kMessageBufferSize);
+  DCHECK(pos_ <= Log::kMessageBufferSize);
 }
 
 
-void LogMessageBuilder::Append(const char c) {
+void Log::MessageBuilder::Append(const char c) {
   if (pos_ < Log::kMessageBufferSize) {
     log_->message_buffer_[pos_++] = c;
   }
-  ASSERT(pos_ <= Log::kMessageBufferSize);
+  DCHECK(pos_ <= Log::kMessageBufferSize);
 }
 
 
-void LogMessageBuilder::Append(String* str) {
-  AssertNoAllocation no_heap_allocation;  // Ensure string stay valid.
+void Log::MessageBuilder::AppendDoubleQuotedString(const char* string) {
+  Append('"');
+  for (const char* p = string; *p != '\0'; p++) {
+    if (*p == '"') {
+      Append('\\');
+    }
+    Append(*p);
+  }
+  Append('"');
+}
+
+
+void Log::MessageBuilder::Append(String* str) {
+  DisallowHeapAllocation no_gc;  // Ensure string stay valid.
   int length = str->length();
   for (int i = 0; i < length; i++) {
     Append(static_cast<char>(str->Get(i)));
@@ -245,22 +153,34 @@
 }
 
 
-void LogMessageBuilder::AppendAddress(Address addr) {
+void Log::MessageBuilder::AppendAddress(Address addr) {
   Append("0x%" V8PRIxPTR, addr);
 }
 
 
-void LogMessageBuilder::AppendDetailed(String* str, bool show_impl_info) {
+void Log::MessageBuilder::AppendSymbolName(Symbol* symbol) {
+  DCHECK(symbol);
+  Append("symbol(");
+  if (!symbol->name()->IsUndefined()) {
+    Append("\"");
+    AppendDetailed(String::cast(symbol->name()), false);
+    Append("\" ");
+  }
+  Append("hash %x)", symbol->Hash());
+}
+
+
+void Log::MessageBuilder::AppendDetailed(String* str, bool show_impl_info) {
   if (str == NULL) return;
-  AssertNoAllocation no_heap_allocation;  // Ensure string stay valid.
+  DisallowHeapAllocation no_gc;  // Ensure string stay valid.
   int len = str->length();
   if (len > 0x1000)
     len = 0x1000;
   if (show_impl_info) {
-    Append(str->IsAsciiRepresentation() ? 'a' : '2');
+    Append(str->IsOneByteRepresentation() ? 'a' : '2');
     if (StringShape(str).IsExternal())
       Append('e');
-    if (StringShape(str).IsSymbol())
+    if (StringShape(str).IsInternalized())
       Append('#');
     Append(":%i:", str->length());
   }
@@ -283,22 +203,26 @@
 }
 
 
-void LogMessageBuilder::AppendStringPart(const char* str, int len) {
+void Log::MessageBuilder::AppendStringPart(const char* str, int len) {
   if (pos_ + len > Log::kMessageBufferSize) {
     len = Log::kMessageBufferSize - pos_;
-    ASSERT(len >= 0);
+    DCHECK(len >= 0);
     if (len == 0) return;
   }
   Vector<char> buf(log_->message_buffer_ + pos_,
                    Log::kMessageBufferSize - pos_);
-  OS::StrNCpy(buf, str, len);
+  StrNCpy(buf, str, len);
   pos_ += len;
-  ASSERT(pos_ <= Log::kMessageBufferSize);
+  DCHECK(pos_ <= Log::kMessageBufferSize);
 }
 
 
-void LogMessageBuilder::WriteToLogFile() {
-  ASSERT(pos_ <= Log::kMessageBufferSize);
+void Log::MessageBuilder::WriteToLogFile() {
+  DCHECK(pos_ <= Log::kMessageBufferSize);
+  // Assert that we do not already have a new line at the end.
+  DCHECK(pos_ == 0 || log_->message_buffer_[pos_ - 1] != '\n');
+  if (pos_ == Log::kMessageBufferSize) pos_--;
+  log_->message_buffer_[pos_++] = '\n';
   const int written = log_->WriteToFile(log_->message_buffer_, pos_);
   if (written != pos_) {
     log_->stop();