diff --git a/pkgs/development/interpreters/ruby/gem.nix b/pkgs/development/interpreters/ruby/gem.nix
index e07ae1ac0f0..3e5057ef1d0 100644
--- a/pkgs/development/interpreters/ruby/gem.nix
+++ b/pkgs/development/interpreters/ruby/gem.nix
@@ -4,12 +4,10 @@
 , namePrefix ? "ruby${ruby.majorVersion}" + "-"
 , buildInputs ? []
 , doCheck ? false
-, doGitPrecheckHack ? false
+, dontBuild ? true
 , meta ? {}
 , gemPath ? []
 , testTask ? "test"
-, preCheck ? ""
-, postCheck ? ""
 , ...} @ attrs:
 
 let
@@ -32,35 +30,23 @@ in ruby.stdenv.mkDerivation (attrs // {
 
   unpackPhase = ''
     gem unpack $src --target=gem-build
+    cd gem-build/*
   '';
 
-  dontBuild = true;
-
-  preCheckGit = ruby.stdenv.lib.optionalString doGitPrecheckHack ''
+  buildPhase = ''
+    runHook preBuild
     ${git}/bin/git init
     ${git}/bin/git add .
+    if gem build *.gemspec; then
+      export src=*.gem
+    else
+      echo >&2 "gemspec missing, not rebuilding gem"
+    fi
+    runHook postBuild
   '';
 
-  preCheck = ''
-    cd gem-build/*
-    OLD_PATH="$GEM_PATH"
-    export GEM_PATH="${depsPath}"
-  '' + preCheck;
-
-  postCheck = ''
-    GEM_PATH="$OLD_PATH"
-  '' + postCheck;
-
-  checkPhase =
-    if attrs ? checkPhase then attrs.checkPhase
-    else ''
-      runHook preCheckGit
-      runHook preCheck
-      test -f Rakefile && ${rake}/bin/rake ${testTask} -v
-      runHook postCheck
-    '';
-
   installPhase = ''
+    runHook preInstall
     GEM_HOME=$out/${ruby.gemPath} \
       gem install -p http://nodtd.invalid \
       --build-root / -n "$out/bin" "$src" $gemFlags -- $buildFlags
@@ -85,7 +71,9 @@ in ruby.stdenv.mkDerivation (attrs // {
     mkdir -p $out/nix-support
 
     cat > $out/nix-support/setup-hook <<EOF
-    addToSearchPath GEM_PATH $out/${ruby.gemPath}
+    if [[ "$GEM_PATH" != *$out/${ruby.gemPath}* ]]; then
+      addToSearchPath GEM_PATH $out/${ruby.gemPath}
+    fi
     EOF
 
     runHook postInstall
diff --git a/pkgs/development/interpreters/ruby/gems.nix b/pkgs/development/interpreters/ruby/gems.nix
index db1bdc357b3..76c43e53567 100644
--- a/pkgs/development/interpreters/ruby/gems.nix
+++ b/pkgs/development/interpreters/ruby/gems.nix
@@ -14,7 +14,6 @@
 
 let
   buildRubyGem = callPackage ./gem.nix {};
-  patches = callPackage ./patches.nix { gems = self; };
   lib = ruby.stdenv.lib;
 self = rec {
   inherit buildRubyGem;
@@ -22,6 +21,7 @@ self = rec {
   # import an attrset full of gems, then override badly behaved ones
   importGems = file: args:
     let
+      patches = callPackage ./patches.nix { gems = builtGems; };
       preBuilt = callPackage file ({ inherit buildRubyGem; self = builtGems; } // args);
       builtGems = self // (lib.mapAttrs (gem: deriv:
         if patches ? "${gem}"
diff --git a/pkgs/development/interpreters/ruby/patches.nix b/pkgs/development/interpreters/ruby/patches.nix
index 4b9f42fb989..3a0a330e6d4 100644
--- a/pkgs/development/interpreters/ruby/patches.nix
+++ b/pkgs/development/interpreters/ruby/patches.nix
@@ -1,8 +1,9 @@
 { fetchurl, writeScript, ruby, ncurses, sqlite, libxml2, libxslt, libffi
 , zlib, libuuid, gems, jdk, python, stdenv, libiconvOrEmpty, imagemagick
-, pkgconfig, libiconv }:
+, gnumake, pkgconfig, which, postgresql, v8_3_16_14, clang }:
 
 let
+  v8 = v8_3_16_14;
 
   patchUsrBinEnv = writeScript "path-usr-bin-env" ''
     #!/bin/sh
@@ -14,111 +15,47 @@ let
 in
 
 {
-  buildr = {
-    # Many Buildfiles rely on RUBYLIB containing the current directory
-    # (as was the default in Ruby < 1.9.2).
-    extraWrapperFlags = "--prefix RUBYLIB : .";
-  };
-
-  barber = { gemFlags = "--ignore-dependencies"; };
+  barber = { gemFlags = "--ignore-dependencies"; dontBuild = 1; };
   ember_data_source = { gemFlags = "--ignore-dependencies"; };
   ember_rails = { gemFlags = "--ignore-dependencies"; };
 
-  fakes3 = {
-    postInstall = ''
-      cd $out/${ruby.gemPath}/gems/*
-      patch -Np1 -i ${../../ruby-modules/fake-s3-list-bucket.patch}
-    '';
-  };
+  rbtrace = { dontBuild = 1; };
+  method_source = { dontBuild = 1; };
 
-  ffi = {
-    postUnpack = "onetuh";
-    buildFlags = ["--with-ffi-dir=${libffi}"];
-    NIX_POST_EXTRACT_FILES_HOOK = patchUsrBinEnv;
-  };
-
-  iconv = { buildInputs = [ libiconvOrEmpty ]; };
-
-  libv8 = {
-    # This fix is needed to fool scons, which clears the environment by default.
-    # It's ugly, but it works.
-    #
-    # We create a gcc wrapper wrapper, which reexposes the environment variables
-    # that scons hides. Furthermore, they treat warnings as errors causing the
-    # build to fail, due to an unused variable.
-    #
-    # Finally, we must set CC and AR explicitly to allow scons to find the
-    # compiler and archiver
-
-    preBuild = ''
-      cat > $TMPDIR/g++ <<EOF
-      #! ${stdenv.shell}
-      $(export)
-
-      g++ \$(echo \$@ | sed 's/-Werror//g')
-      EOF
-      chmod +x $TMPDIR/g++
-
-      export CXX=$TMPDIR/g++
-      export AR=$(type -p ar)
-    '';
-    buildInputs = [ python ];
-    NIX_POST_EXTRACT_FILES_HOOK = writeScript "patch-scons" ''
-      #!/bin/sh
-      for i in `find "$1" -name scons`
-      do
-          sed -i -e "s@/usr/bin/env@$(type -p env)@g" $i
-      done
-    '';
-  };
-
-  ncurses = { propagatedBuildInputs = [ ncurses ]; };
-
-  ncursesw = { propagatedBuildInputs = [ ncurses ]; };
-
-  nix = {
-    postInstall = ''
-      cd $out/${ruby.gemPath}/gems/nix*
-      patch -Np1 -i ${./fix-gem-nix-versions.patch}
-    '';
-  };
+  pg = { buildInputs = [ postgresql ]; };
 
   nokogiri = {
     buildInputs = [ libxml2 ];
     buildFlags =
       [ "--with-xml2-dir=${libxml2} --with-xml2-include=${libxml2}/include/libxml2"
-        "--with-xslt-dir=${libxslt} --with-iconv-dir=${libiconv} --use-system-libraries"
+        "--with-xslt-dir=${libxslt}" "--use-system-libraries"
       ];
   };
 
-  pry = { gemFlags = "--no-ri --no-rdoc"; };
+  therubyracer = {
+    preBuild = ''
+      addToSearchPath RUBYLIB "${gems.libv8}/${ruby.gemPath}/gems/libv8-3.16.14.3/lib"
+      addToSearchPath RUBYLIB "${gems.libv8}/${ruby.gemPath}/gems/libv8-3.16.14.3/ext"
+      ln -s ${clang}/bin/clang $TMPDIR/gcc
+      ln -s ${clang}/bin/clang++ $TMPDIR/g++
+      export PATH=$TMPDIR:$PATH
+    '';
 
-  rails = { gemFlags = "--no-ri --no-rdoc"; };
+    postInstall = stdenv.lib.optionalString stdenv.isDarwin ''
+      cat >> $out/nix-support/setup-hook <<EOF
+        addToSearchPath DYLD_INSERT_LIBRARIES "${v8}/lib/libv8.dylib"
+      EOF
+    '';
 
-  rjb = {
-    buildInputs = [ jdk ];
-    JAVA_HOME = jdk;
+    buildFlags = [
+      "--with-v8-dir=${v8}" "--with-v8-include=${v8}/include"
+      "--with-v8-lib=${v8}/lib"
+    ];
   };
 
-  rmagick = {
-    buildInputs = [ imagemagick pkgconfig ];
-
-    NIX_CFLAGS_COMPILE = "-I${imagemagick}/include/ImageMagick-6";
-  };
-
-  sqlite3 = { propagatedBuildInputs = [ sqlite ]; };
-
-  xapian_full = {
-    buildInputs = [ gems.rake zlib libuuid ];
-    gemFlags = "--no-rdoc --no-ri";
-  };
-
-  xapian_full_alaveteli = {
-    buildInputs = [ zlib libuuid ];
-  };
-
-  xapian_ruby = {
-    buildInputs = [ zlib libuuid ];
+  libv8 = {
+    dontBuild = true;
+    buildFlags = [ "--with-system-v8" ];
   };
 
   xrefresh_server =
diff --git a/pkgs/development/libraries/v8/3.16.14.nix b/pkgs/development/libraries/v8/3.16.14.nix
new file mode 100644
index 00000000000..436df768eb3
--- /dev/null
+++ b/pkgs/development/libraries/v8/3.16.14.nix
@@ -0,0 +1,69 @@
+{ stdenv, fetchurl, gyp, readline, python, which, icu }:
+
+assert readline != null;
+
+let
+  arch = if stdenv.is64bit then "x64" else "ia32";
+in
+
+stdenv.mkDerivation rec {
+  name = "v8-${version}";
+  version = "3.16.14";
+
+  src = fetchurl {
+    url = "https://commondatastorage.googleapis.com/chromium-browser-official/"
+        + "${name}.tar.bz2";
+    sha256 = "073f33zcb7205jp9g5ha5d7j2hfa98zs0jql572nb552z0xw3rkz";
+  };
+
+  configurePhase = stdenv.lib.optionalString stdenv.isDarwin ''
+    ln -s /usr/bin/xcodebuild $TMPDIR
+    export PATH=$TMPDIR:$PATH
+  '' + ''
+    PYTHONPATH="tools/generate_shim_headers:$PYTHONPATH" \
+      ${gyp}/bin/gyp \
+        -f make \
+        --generator-output="out" \
+        -Dflock_index=0 \
+        -Dv8_enable_i18n_support=1 \
+        -Duse_system_icu=1 \
+        -Dconsole=readline \
+        -Dcomponent=shared_library \
+        -Dv8_target_arch=${arch} \
+        --depth=. -Ibuild/standalone.gypi \
+        build/all.gyp
+  '';
+
+  nativeBuildInputs = [ which ];
+  buildInputs = [ readline python icu ];
+
+  buildFlags = [
+    "LINK=g++"
+    "-C out"
+    "builddir=$(CURDIR)/Release"
+    "BUILDTYPE=Release"
+  ];
+
+  enableParallelBuilding = true;
+
+  installPhase = ''
+    install -vD out/Release/d8 "$out/bin/d8"
+    ${if stdenv.system == "x86_64-darwin" then ''
+    install -vD out/Release/libv8.dylib "$out/lib/libv8.dylib"
+    '' else ''
+    install -vD out/Release/libv8.so "$out/lib/libv8.so"
+    ''}
+    cp -vr include "$out/"
+  '';
+
+  postFixup = if stdenv.isDarwin then ''
+    install_name_tool -change /usr/local/lib/libv8.dylib $out/lib/libv8.dylib -change /usr/lib/libgcc_s.1.dylib ${stdenv.gcc.gcc}/lib/libgcc_s.1.dylib $out/bin/d8
+    install_name_tool -id $out/lib/libv8.dylib -change /usr/lib/libgcc_s.1.dylib ${stdenv.gcc.gcc}/lib/libgcc_s.1.dylib $out/lib/libv8.dylib
+  '' else null;
+
+  meta = with stdenv.lib; {
+    description = "V8 is Google's open source JavaScript engine";
+    platforms = platforms.linux ++ platforms.darwin;
+    license = licenses.bsd3;
+  };
+}
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 2fdddc9e21a..7da37f7226d 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -6790,6 +6790,10 @@ let
 
   ucommon = callPackage ../development/libraries/ucommon { };
 
+  v8_3_16_14 = callPackage ../development/libraries/v8/3.16.14.nix {
+    inherit (pythonPackages) gyp;
+  };
+
   v8 = callPackage ../development/libraries/v8 {
     inherit (pythonPackages) gyp;
   };