diff --git a/Library/Homebrew/extend/ENV.rb b/Library/Homebrew/extend/ENV.rb
index 22ca501e41..f77d0007e0 100644
--- a/Library/Homebrew/extend/ENV.rb
+++ b/Library/Homebrew/extend/ENV.rb
@@ -22,11 +22,14 @@ module HomebrewEnvExtension
     # Os is the default Apple uses for all its stuff so let's trust them
     self['CFLAGS'] = self['CXXFLAGS'] = "-Os #{SAFE_CFLAGS_FLAGS}"
 
+    # set us up for the user's compiler choice
     self.send self.compiler
+
     # we must have a working compiler!
     unless File.exist? ENV['CC'] and File.exist? ENV['CXX']
       @compiler = MacOS.default_compiler
       self.send @compiler
+
       ENV['CC']  = '/usr/bin/cc'
       ENV['CXX'] = '/usr/bin/c++'
     end
@@ -75,8 +78,8 @@ module HomebrewEnvExtension
   end
 
   def gcc_4_0_1
-    self['CC'] = '/usr/bin/gcc-4.0'
-    self['CXX'] = '/usr/bin/g++-4.0'
+    self['CC'] =  "#{MacOS.dev_tools_path}/gcc-4.0"
+    self['CXX'] = "#{MacOS.dev_tools_path}/g++-4.0"
     replace_in_cflags '-O4', '-O3'
     set_cpu_cflags 'nocona -mssse3', :core => 'prescott', :bottle => 'generic'
     @compiler = :gcc
@@ -84,8 +87,12 @@ module HomebrewEnvExtension
   alias_method :gcc_4_0, :gcc_4_0_1
 
   def gcc args = {}
-    gcc_path = Pathname.new "/usr/bin/gcc-4.2"
-    gxx_path = Pathname.new "/usr/bin/g++-4.2"
+    # Apple stopped shipping gcc-4.2 with Xcode 4.2
+    # However they still provide a gcc symlink to llvm
+    # But we don't want LLVM of course.
+
+    gcc_path = Pathname.new "#{MacOS.dev_tools_path}/gcc-4.2"
+    gxx_path = Pathname.new "#{MacOS.dev_tools_path}/g++-4.2"
     self['CC']  = gcc_path.exist? ? gcc_path : HOMEBREW_PREFIX+'bin/gcc-4.2'
     self['CXX'] = gxx_path.exist? ? gxx_path : HOMEBREW_PREFIX+'bin/g++-4.2'
     replace_in_cflags '-O4', '-O3'
@@ -98,15 +105,15 @@ module HomebrewEnvExtension
   alias_method :gcc_4_2, :gcc
 
   def llvm
-    self['CC']  = "/usr/bin/llvm-gcc"
-    self['CXX'] = "/usr/bin/llvm-g++"
+    self['CC']  = "#{MacOS.dev_tools_path}/llvm-gcc"
+    self['CXX'] = "#{MacOS.dev_tools_path}/llvm-g++"
     set_cpu_cflags 'core2 -msse4', :penryn => 'core2 -msse4.1', :core2 => 'core2', :core => 'prescott'
     @compiler = :llvm
   end
 
   def clang args = {}
-    self['CC']  = "/usr/bin/clang"
-    self['CXX'] = "/usr/bin/clang++"
+    self['CC']  = "#{MacOS.dev_tools_path}/clang"
+    self['CXX'] = "#{MacOS.dev_tools_path}/clang++"
     replace_in_cflags(/-Xarch_i386 (-march=\S*)/, '\1')
     # Clang mistakenly enables AES-NI on plain Nehalem
     set_cpu_cflags 'native', :nehalem => 'native -Xclang -target-feature -Xclang -aes'
diff --git a/Library/Homebrew/utils.rb b/Library/Homebrew/utils.rb
index c7da0db6ca..452f1fd138 100644
--- a/Library/Homebrew/utils.rb
+++ b/Library/Homebrew/utils.rb
@@ -251,8 +251,29 @@ module MacOS extend self
     MACOS_VERSION
   end
 
+  def dev_tools_path
+    @dev_tools_path ||= if File.file? "/usr/bin/cc" and File.file? "/usr/bin/make"
+      # probably a safe enough assumption
+      "/usr/bin"
+    elsif File.file? "#{xcode_prefix}/usr/bin/make"
+      # cc stopped existing with Xcode 4.3, there are c89 and c99 options though
+      "#{xcode_prefix}/usr/bin"
+    else
+      # yes this seems dumb, but we can't throw because the existance of
+      # dev tools is not mandatory for installing formula. Eventually we
+      # should make forumla specify if they need dev tools or not.
+      "/usr/bin"
+    end
+  end
+
   def default_cc
-    Pathname.new("/usr/bin/cc").realpath.basename.to_s
+    cc = if !File.file? "/usr/bin/cc" and xcode_version > 4.3
+      # there is no cc file in Xcode 4.3.0 in the /Developer/usr/bin directory
+      "llvm-gcc"
+    else
+      "cc"
+    end
+    Pathname.new("#{dev_tools_path}/cc").realpath.basename.to_s
   end
 
   def default_compiler
@@ -260,21 +281,27 @@ module MacOS extend self
       when /^gcc/ then :gcc
       when /^llvm/ then :llvm
       when "clang" then :clang
-      else :gcc # a hack, but a sensible one prolly
+      else
+        # guess :(
+        if xcode_version > 4.2
+          :llvm
+        else
+          :gcc
+        end
     end
   end
 
   def gcc_42_build_version
-    @gcc_42_build_version ||= if File.exist? "/usr/bin/gcc-4.2" \
-      and not Pathname.new("/usr/bin/gcc-4.2").realpath.basename.to_s =~ /^llvm/
-      `/usr/bin/gcc-4.2 --version` =~ /build (\d{4,})/
+    @gcc_42_build_version ||= if File.exist? "#{dev_tools_path}/gcc-4.2" \
+      and not Pathname.new("#{dev_tools_path}/gcc-4.2").realpath.basename.to_s =~ /^llvm/
+      `#{dev_tools_path}/gcc-4.2 --version` =~ /build (\d{4,})/
       $1.to_i
     end
   end
 
   def gcc_40_build_version
-    @gcc_40_build_version ||= if File.exist? "/usr/bin/gcc-4.0"
-      `/usr/bin/gcc-4.0 --version` =~ /build (\d{4,})/
+    @gcc_40_build_version ||= if File.exist? "#{dev_tools_path}/gcc-4.0"
+      `#{dev_tools_path}/gcc-4.0 --version` =~ /build (\d{4,})/
       $1.to_i
     end
   end
@@ -332,22 +359,22 @@ module MacOS extend self
   def llvm_build_version
     # for Xcode 3 on OS X 10.5 this will not exist
     # NOTE may not be true anymore but we can't test
-    @llvm_build_version ||= if File.exist? "/usr/bin/llvm-gcc"
-      `/usr/bin/llvm-gcc --version` =~ /LLVM build (\d{4,})/
+    @llvm_build_version ||= if File.exist? "#{dev_tools_path}/llvm-gcc"
+      `#{dev_tools_path}/llvm-gcc --version` =~ /LLVM build (\d{4,})/
       $1.to_i
     end
   end
 
   def clang_version
-    @clang_version ||= if File.exist? "/usr/bin/clang"
-      `/usr/bin/clang --version` =~ /clang version (\d\.\d)/
+    @clang_version ||= if File.exist? "#{dev_tools_path}/clang"
+      `#{dev_tools_path}/clang --version` =~ /clang version (\d\.\d)/
       $1
     end
   end
 
   def clang_build_version
-    @clang_build_version ||= if File.exist? "/usr/bin/clang"
-      `/usr/bin/clang --version` =~ %r[tags/Apple/clang-(\d{2,})]
+    @clang_build_version ||= if File.exist? "#{dev_tools_path}/clang"
+      `#{dev_tools_path}/clang --version` =~ %r[tags/Apple/clang-(\d{2,})]
       $1.to_i
     end
   end