diff --git a/Rakefile b/Rakefile
index ce3da1d9a9..6ccdcd9587 100644
--- a/Rakefile
+++ b/Rakefile
@@ -14,7 +14,8 @@ require "mruby-core-ext"
 require "mruby/build"
 
 # load configuration file
-MRUBY_CONFIG = (ENV['MRUBY_CONFIG'] && ENV['MRUBY_CONFIG'] != '') ? ENV['MRUBY_CONFIG'] : "#{MRUBY_ROOT}/build_config.rb"
+MRUBY_TARGET = ENV['MRUBY_TARGET'] || ENV['TARGET'] || "host"
+MRUBY_CONFIG = "#{MRUBY_ROOT}/target/#{MRUBY_TARGET}.rb"
 load MRUBY_CONFIG
 
 # load basic rules
diff --git a/lib/mruby/lockfile.rb b/lib/mruby/lockfile.rb
index 0d2455b4c4..ee16e2ad8b 100644
--- a/lib/mruby/lockfile.rb
+++ b/lib/mruby/lockfile.rb
@@ -26,7 +26,7 @@ def write
       end
 
       def instance
-        @instance ||= new("#{MRUBY_CONFIG}.lock")
+        @instance ||= new("#{MRUBY_ROOT}/build/#{MRUBY_TARGET}.lock")
       end
     end
 
diff --git a/examples/targets/build_config_ArduinoDue.rb b/target/ArduinoDue.rb
similarity index 100%
rename from examples/targets/build_config_ArduinoDue.rb
rename to target/ArduinoDue.rb
diff --git a/examples/targets/build_config_IntelEdison.rb b/target/IntelEdison.rb
similarity index 100%
rename from examples/targets/build_config_IntelEdison.rb
rename to target/IntelEdison.rb
diff --git a/examples/targets/build_config_IntelGalileo.rb b/target/IntelGalileo.rb
similarity index 100%
rename from examples/targets/build_config_IntelGalileo.rb
rename to target/IntelGalileo.rb
diff --git a/examples/targets/build_config_RX630.rb b/target/RX630.rb
similarity index 100%
rename from examples/targets/build_config_RX630.rb
rename to target/RX630.rb
diff --git a/examples/targets/build_config_android_arm64-v8a.rb b/target/android_arm64-v8a.rb
similarity index 100%
rename from examples/targets/build_config_android_arm64-v8a.rb
rename to target/android_arm64-v8a.rb
diff --git a/examples/targets/build_config_android_armeabi.rb b/target/android_armeabi.rb
similarity index 100%
rename from examples/targets/build_config_android_armeabi.rb
rename to target/android_armeabi.rb
diff --git a/examples/targets/build_config_android_armeabi_v7a_neon_hard.rb b/target/android_armeabi_v7a_neon_hard.rb
similarity index 100%
rename from examples/targets/build_config_android_armeabi_v7a_neon_hard.rb
rename to target/android_armeabi_v7a_neon_hard.rb
diff --git a/appveyor_config.rb b/target/appveyor.rb
similarity index 100%
rename from appveyor_config.rb
rename to target/appveyor.rb
diff --git a/target/bench.rb b/target/bench.rb
new file mode 100644
index 0000000000..30ec56ad3c
--- /dev/null
+++ b/target/bench.rb
@@ -0,0 +1,11 @@
+MRuby::Build.new('bench') do |conf|
+  # Gets set by the VS command prompts.
+  if ENV['VisualStudioVersion'] || ENV['VSINSTALLDIR']
+    toolchain :visualcpp
+  else
+    toolchain :gcc
+    conf.cc.flags << '-O3'
+  end
+
+  conf.gembox 'default'
+end
diff --git a/examples/targets/build_config_chipKITMax32.rb b/target/chipKITMax32.rb
similarity index 100%
rename from examples/targets/build_config_chipKITMax32.rb
rename to target/chipKITMax32.rb
diff --git a/target/cross-32bit.rb b/target/cross-32bit.rb
new file mode 100644
index 0000000000..310ffc833a
--- /dev/null
+++ b/target/cross-32bit.rb
@@ -0,0 +1,13 @@
+# Define cross build settings
+MRuby::CrossBuild.new('32bit') do |conf|
+  toolchain :gcc
+
+  conf.cc.flags << "-m32"
+  conf.linker.flags << "-m32"
+
+  conf.build_mrbtest_lib_only
+
+  conf.gem 'examples/mrbgems/c_and_ruby_extension_example'
+
+  conf.test_runner.command = 'env'
+end
diff --git a/examples/targets/build_config_dreamcast_shelf.rb b/target/dreamcast_shelf.rb
similarity index 100%
rename from examples/targets/build_config_dreamcast_shelf.rb
rename to target/dreamcast_shelf.rb
diff --git a/target/host-debug.rb b/target/host-debug.rb
new file mode 100644
index 0000000000..4e89d162c7
--- /dev/null
+++ b/target/host-debug.rb
@@ -0,0 +1,24 @@
+MRuby::Build.new('host-debug') do |conf|
+  # load specific toolchain settings
+
+  # Gets set by the VS command prompts.
+  if ENV['VisualStudioVersion'] || ENV['VSINSTALLDIR']
+    toolchain :visualcpp
+  else
+    toolchain :gcc
+  end
+
+  enable_debug
+
+  # include the default GEMs
+  conf.gembox 'full-core'
+
+  # C compiler settings
+  conf.cc.defines = %w(MRB_ENABLE_DEBUG_HOOK)
+
+  # Generate mruby debugger command (require mruby-eval)
+  conf.gem :core => "mruby-bin-debugger"
+
+  # bintest
+  # conf.enable_bintest
+end
diff --git a/build_config.rb b/target/host.rb
similarity index 70%
rename from build_config.rb
rename to target/host.rb
index 254a28ce01..4f02868823 100644
--- a/build_config.rb
+++ b/target/host.rb
@@ -8,9 +8,6 @@
     toolchain :gcc
   end
 
-  # Turn on `enable_debug` for better debugging
-  # enable_debug
-
   # Use mrbgems
   # conf.gem 'examples/mrbgems/ruby_extension_example'
   # conf.gem 'examples/mrbgems/c_extension_example' do |g|
@@ -22,8 +19,9 @@
   # conf.gem :github => 'mattn/mruby-onig-regexp'
   # conf.gem :git => 'git@github.com:mattn/mruby-onig-regexp.git', :branch => 'master', :options => '-v'
 
-  # include the default GEMs
-  conf.gembox 'default'
+  # include the GEM box
+  conf.gembox 'full-core'
+
   # C compiler settings
   # conf.cc do |cc|
   #   cc.command = ENV['CC'] || 'gcc'
@@ -81,33 +79,11 @@
   # file separetor
   # conf.file_separator = '/'
 
-  # bintest
-  # conf.enable_bintest
-end
-
-MRuby::Build.new('host-debug') do |conf|
-  # load specific toolchain settings
-
-  # Gets set by the VS command prompts.
-  if ENV['VisualStudioVersion'] || ENV['VSINSTALLDIR']
-    toolchain :visualcpp
-  else
-    toolchain :gcc
-  end
-
+  # Turn on `enable_debug` for better debugging
+  # enable_debug
   enable_debug
-
-  # include the default GEMs
-  conf.gembox 'default'
-
-  # C compiler settings
-  conf.cc.defines = %w(MRB_ENABLE_DEBUG_HOOK)
-
-  # Generate mruby debugger command (require mruby-eval)
-  conf.gem :core => "mruby-bin-debugger"
-
-  # bintest
-  # conf.enable_bintest
+  conf.enable_bintest
+  conf.enable_test
 end
 
 MRuby::Build.new('test') do |conf|
@@ -118,35 +94,5 @@
     toolchain :gcc
   end
 
-  enable_debug
-  conf.enable_bintest
-  conf.enable_test
-
   conf.gembox 'default'
 end
-
-#MRuby::Build.new('bench') do |conf|
-#  # Gets set by the VS command prompts.
-#  if ENV['VisualStudioVersion'] || ENV['VSINSTALLDIR']
-#    toolchain :visualcpp
-#  else
-#    toolchain :gcc
-#    conf.cc.flags << '-O3'
-#  end
-#
-#  conf.gembox 'default'
-#end
-
-# Define cross build settings
-# MRuby::CrossBuild.new('32bit') do |conf|
-#   toolchain :gcc
-#
-#   conf.cc.flags << "-m32"
-#   conf.linker.flags << "-m32"
-#
-#   conf.build_mrbtest_lib_only
-#
-#   conf.gem 'examples/mrbgems/c_and_ruby_extension_example'
-#
-#   conf.test_runner.command = 'env'
-# end
diff --git a/travis_config.rb b/target/travis.rb
similarity index 100%
rename from travis_config.rb
rename to target/travis.rb
diff --git a/tasks/benchmark.rake b/tasks/benchmark.rake
index 6352f5c179..661fd2ada6 100644
--- a/tasks/benchmark.rake
+++ b/tasks/benchmark.rake
@@ -9,11 +9,7 @@ def bm_files
 end
 
 def build_config_name
-  if ENV['MRUBY_CONFIG']
-    File.basename(ENV['MRUBY_CONFIG'], '.rb').gsub('build_config_', '')
-  else
-    "build"
-  end
+  MRUBY_TARGET
 end
 
 def plot_file