diff --git a/deps/v8/include/v8-version.h b/deps/v8/include/v8-version.h
index e0027b224ea79a..4d5266ba421bc6 100644
--- a/deps/v8/include/v8-version.h
+++ b/deps/v8/include/v8-version.h
@@ -11,7 +11,7 @@
 #define V8_MAJOR_VERSION 5
 #define V8_MINOR_VERSION 0
 #define V8_BUILD_NUMBER 71
-#define V8_PATCH_LEVEL 57
+#define V8_PATCH_LEVEL 58
 
 // Use 1 for candidates and 0 otherwise.
 // (Boolean macro values are not supported by all preprocessors.)
diff --git a/deps/v8/src/log.cc b/deps/v8/src/log.cc
index cbdd9dd106024d..86de99d06da22c 100644
--- a/deps/v8/src/log.cc
+++ b/deps/v8/src/log.cc
@@ -248,10 +248,6 @@ class PerfBasicLogger : public CodeEventLogger {
   static const char kFilenameFormatString[];
   static const int kFilenameBufferPadding;
 
-  // File buffer size of the low-level log. We don't use the default to
-  // minimize the associated overhead.
-  static const int kLogBufferSize = 2 * MB;
-
   FILE* perf_output_handle_;
 };
 
@@ -272,7 +268,7 @@ PerfBasicLogger::PerfBasicLogger()
   perf_output_handle_ =
       base::OS::FOpen(perf_dump_name.start(), base::OS::LogFileOpenMode);
   CHECK_NOT_NULL(perf_output_handle_);
-  setvbuf(perf_output_handle_, NULL, _IOFBF, kLogBufferSize);
+  setvbuf(perf_output_handle_, NULL, _IOLBF, 0);
 }
 
 
@@ -359,10 +355,6 @@ class LowLevelLogger : public CodeEventLogger {
   // Extension added to V8 log file name to get the low-level log name.
   static const char kLogExt[];
 
-  // File buffer size of the low-level log. We don't use the default to
-  // minimize the associated overhead.
-  static const int kLogBufferSize = 2 * MB;
-
   void LogCodeInfo();
   void LogWriteBytes(const char* bytes, int size);
 
@@ -387,7 +379,7 @@ LowLevelLogger::LowLevelLogger(const char* name)
   MemCopy(ll_name.start() + len, kLogExt, sizeof(kLogExt));
   ll_output_handle_ =
       base::OS::FOpen(ll_name.start(), base::OS::LogFileOpenMode);
-  setvbuf(ll_output_handle_, NULL, _IOFBF, kLogBufferSize);
+  setvbuf(ll_output_handle_, NULL, _IOLBF, 0);
 
   LogCodeInfo();
 }