diff --git a/deps/v8/build/common.gypi b/deps/v8/build/common.gypi
index 426d625675..44cab4d0cb 100644
--- a/deps/v8/build/common.gypi
+++ b/deps/v8/build/common.gypi
@@ -274,8 +274,7 @@
           },
         },
       }],
-      ['OS=="linux" or OS=="freebsd" or OS=="openbsd" or OS=="solaris" \
-         or OS=="netbsd"', {
+      ['OS in "linux freebsd dragonflybsd openbsd solaris netbsd".split()', {
         'conditions': [
           [ 'v8_no_strict_aliasing==1', {
             'cflags': [ '-fno-strict-aliasing' ],
@@ -285,8 +284,8 @@
       ['OS=="solaris"', {
         'defines': [ '__C99FEATURES__=1' ],  # isinf() etc.
       }],
-      ['(OS=="linux" or OS=="freebsd" or OS=="openbsd" or OS=="solaris" \
-         or OS=="netbsd" or OS=="mac" or OS=="android") and \
+      ['(OS=="linux" or OS=="freebsd" or OS=="dragonflybsd" or OS=="openbsd" \
+         or OS=="solaris" or OS=="netbsd" or OS=="mac" or OS=="android") and \
         (v8_target_arch=="arm" or v8_target_arch=="ia32" or \
          v8_target_arch=="mipsel")', {
         # Check whether the host compiler and target compiler support the
@@ -314,7 +313,7 @@
           }],
         ],
       }],
-      ['OS=="freebsd" or OS=="openbsd"', {
+      ['OS=="freebsd" or OS=="dragonflybsd" or OS=="openbsd"', {
         'cflags': [ '-I/usr/local/include' ],
       }],
       ['OS=="netbsd"', {
@@ -346,7 +345,7 @@
           },
         },
         'conditions': [
-          ['OS=="linux" or OS=="freebsd" or OS=="openbsd" or OS=="netbsd"', {
+          ['OS in "linux freebsd dragonflybsd openbsd netbsd".split()', {
             'cflags': [ '-Wall', '<(werror)', '-W', '-Wno-unused-parameter',
                         '-Wnon-virtual-dtor', '-Woverloaded-virtual' ],
           }],
@@ -368,8 +367,8 @@
       },  # Debug
       'Release': {
         'conditions': [
-          ['OS=="linux" or OS=="freebsd" or OS=="openbsd" or OS=="netbsd" \
-            or OS=="android"', {
+          ['OS=="linux" or OS=="freebsd" or OS=="dragonflybsd" \
+            or OS=="openbsd" or OS=="netbsd" or OS=="android"', {
             'conditions': [
               [ 'gcc_version==44 and clang==0', {
                 'cflags': [
diff --git a/deps/v8/build/standalone.gypi b/deps/v8/build/standalone.gypi
index 7145a16e0c..e6c7088997 100644
--- a/deps/v8/build/standalone.gypi
+++ b/deps/v8/build/standalone.gypi
@@ -38,8 +38,7 @@
       'variables': {
         'variables': {
           'conditions': [
-            ['OS=="linux" or OS=="freebsd" or OS=="openbsd" or \
-               OS=="netbsd" or OS=="mac"', {
+            ['OS!="win"', {
               # This handles the Unix platforms we generally deal with.
               # Anything else gets passed through, which probably won't work
               # very well; such hosts should pass an explicit target_arch
@@ -47,9 +46,8 @@
               'host_arch%':
                 '<!(uname -m | sed -e "s/i.86/ia32/;\
                   s/x86_64/x64/;s/amd64/x64/;s/arm.*/arm/;s/mips.*/mipsel/")',
-            }, {
-              # OS!="linux" and OS!="freebsd" and OS!="openbsd" and
-              # OS!="netbsd" and OS!="mac"
+            }],
+            ['OS=="win"', {
               'host_arch%': 'ia32',
             }],
           ],
@@ -89,8 +87,7 @@
     },
   },
   'conditions': [
-    ['OS=="linux" or OS=="freebsd" or OS=="openbsd" or OS=="solaris" \
-       or OS=="netbsd"', {
+    ['OS!="win"', {
       'target_defaults': {
         'cflags': [ '-Wall', '<(werror)', '-W', '-Wno-unused-parameter',
                     '-Wnon-virtual-dtor', '-pthread', '-fno-rtti',
@@ -109,8 +106,6 @@
         ],
       },
     }],
-    # 'OS=="linux" or OS=="freebsd" or OS=="openbsd" or OS=="solaris"
-    #  or OS=="netbsd"'
     ['OS=="win"', {
       'target_defaults': {
         'defines': [
diff --git a/deps/v8/src/d8.gyp b/deps/v8/src/d8.gyp
index 2aa94ccf92..051b0922b7 100644
--- a/deps/v8/src/d8.gyp
+++ b/deps/v8/src/d8.gyp
@@ -61,8 +61,7 @@
               'libraries': [ '-lreadline', ],
               'sources': [ 'd8-readline.cc' ],
             }],
-            ['(OS=="linux" or OS=="mac" or OS=="freebsd" or OS=="netbsd" \
-               or OS=="openbsd" or OS=="solaris" or OS=="android")', {
+            [ 'OS!="win"', {
               'sources': [ 'd8-posix.cc', ]
             }],
             [ 'OS=="win"', {
diff --git a/deps/v8/src/platform-freebsd.cc b/deps/v8/src/platform-freebsd.cc
index 511759c485..738df11698 100644
--- a/deps/v8/src/platform-freebsd.cc
+++ b/deps/v8/src/platform-freebsd.cc
@@ -43,12 +43,15 @@
 #include <sys/fcntl.h>  // open
 #include <unistd.h>     // getpagesize
 // If you don't have execinfo.h then you need devel/libexecinfo from ports.
-#include <execinfo.h>   // backtrace, backtrace_symbols
 #include <strings.h>    // index
 #include <errno.h>
 #include <stdarg.h>
 #include <limits.h>
 
+#if !defined(__DragonFly__)
+#include <execinfo.h>   // backtrace, backtrace_symbols
+#endif
+
 #undef MAP_TYPE
 
 #include "v8.h"
@@ -296,6 +299,9 @@ void OS::SignalCodeMovingGC() {
 
 
 int OS::StackWalk(Vector<OS::StackFrame> frames) {
+#if defined(__DragonFly__)
+  return 0;
+#else
   int frames_size = frames.length();
   ScopedVector<void*> addresses(frames_size);
 
@@ -320,6 +326,7 @@ int OS::StackWalk(Vector<OS::StackFrame> frames) {
   free(symbols);
 
   return frames_count;
+#endif
 }
 
 
@@ -612,6 +619,13 @@ void FreeBSDSemaphore::Wait() {
 
 
 bool FreeBSDSemaphore::Wait(int timeout) {
+#if defined(__DragonFly__)
+  /* DragonFlyBSD lacks sem_timedwait() and there is no good way to emulate it.
+   */
+  if (sem_wait(&sem_)) abort();
+  USE(timeout);
+  return true;
+#else
   const long kOneSecondMicros = 1000000;  // NOLINT
 
   // Split timeout into second and nanosecond parts.
@@ -637,6 +651,7 @@ bool FreeBSDSemaphore::Wait(int timeout) {
     if (result == -1 && errno == ETIMEDOUT) return false;  // Timeout.
     CHECK(result == -1 && errno == EINTR);  // Signal caused spurious wakeup.
   }
+#endif
 }
 
 
diff --git a/deps/v8/tools/gyp/v8.gyp b/deps/v8/tools/gyp/v8.gyp
index d57672c57a..5d3cad526f 100644
--- a/deps/v8/tools/gyp/v8.gyp
+++ b/deps/v8/tools/gyp/v8.gyp
@@ -678,6 +678,14 @@
                   'libraries': [
                     '-L/usr/local/lib -lexecinfo',
                 ]},
+            }],
+            ['OS=="dragonflybsd"', {
+                'link_settings': {
+                  'libraries': [
+                    '-pthread',
+                ]},
+            }],
+            ['OS=="freebsd" or OS=="dragonflybsd"', {
                 'sources': [
                   '../../src/platform-freebsd.cc',
                   '../../src/platform-posix.cc'