diff --git a/Library/Homebrew/brewkit.rb b/Library/Homebrew/brewkit.rb
index 1ff6e0af23..bc208236a5 100644
--- a/Library/Homebrew/brewkit.rb
+++ b/Library/Homebrew/brewkit.rb
@@ -17,13 +17,38 @@
 
 require 'osx/cocoa' # to get number of cores
 require 'formula'
+require 'hw.model'
+
+ENV['MACOSX_DEPLOYMENT_TARGET']='10.5'
+ENV['CFLAGS']='-O3 -w -pipe -fomit-frame-pointer -mmacosx-version-min=10.5'
+ENV['LDFLAGS']='' # to be consistent, we ignore the environment usually already
 
 # optimise all the way to eleven, references:
 # http://en.gentoo-wiki.com/wiki/Safe_Cflags/Intel
 # http://forums.mozillazine.org/viewtopic.php?f=12&t=577299
-# http://gcc.gnu.org/onlinedocs/gcc-4.0.1/gcc/i386-and-x86_002d64-Options.html
-ENV['MACOSX_DEPLOYMENT_TARGET']='10.5'
-ENV['CFLAGS']=ENV['CXXFLAGS']='-O3 -w -pipe -fomit-frame-pointer -march=prescott -mmacosx-version-min=10.5'
+# http://gcc.gnu.org/onlinedocs/gcc-4.2.1/gcc/i386-and-x86_002d64-Options.html
+case hw_model
+  when :core1
+    # Core DUO is a 32 bit chip
+    ENV['CFLAGS']="#{ENV['CFLAGS']} -march=prescott -mfpmath=sse -msse3 -mmmx"
+  when :core2
+    # Core 2 DUO is a 64 bit chip
+    # GCC 4.3 will have a -march=core2, but for now nocona is correct
+    ENV['CFLAGS']="#{ENV['CFLAGS']} -march=nocona -mfpmath=sse -msse3 -mmmx"
+    
+    # OK so we're not doing 64 bit yet... but we will with Snow Leopard
+    # -mfpmath=sse defaults to on for the x64 compiler
+    #ENV['CFLAGS']="#{ENV['CFLAGS']} -march=nocona -msse3 -mmmx -m64"
+    #ENV['LDFLAGS']="-arch x86_64"
+
+  when :xeon, :macpro
+    # TODO what optimisations for xeon?
+
+  when :ppc   then abort "Sorry, Homebrew does not support PowerPC architectures"
+  when :dunno then abort "Sorry, Homebrew cannot determine what kind of Mac this is!"
+end
+
+ENV['CXXFLAGS']=ENV['CFLAGS']
 
 # lets use gcc 4.2, it is newer and "better", at least I believe so, mail me
 # if I'm wrong
@@ -31,11 +56,13 @@ ENV['CC']='gcc-4.2'
 ENV['CXX']='g++-4.2'
 ENV['MAKEFLAGS']="-j#{OSX::NSProcessInfo.processInfo.processorCount}"
 
+
 unless HOMEBREW_PREFIX == '/usr/local'
   ENV['CPPFLAGS']="-I#{HOMEBREW_PREFIX}/include"
   ENV['LDFLAGS']="-L#{HOMEBREW_PREFIX}/lib"
 end
 
+
 def inreplace(path, before, after)
   before=Regexp.escape before.to_s
   after=Regexp.escape after.to_s
diff --git a/Library/Homebrew/env.rb b/Library/Homebrew/env.rb
index 7ff57071eb..a9cb6aa915 100644
--- a/Library/Homebrew/env.rb
+++ b/Library/Homebrew/env.rb
@@ -18,6 +18,7 @@
 require 'pathname+yeast'
 require 'utils'
 
+# TODO if whoami == root then use /Library/Caches/Homebrew instead
 HOMEBREW_VERSION='0.3'
 HOMEBREW_CACHE=File.expand_path "~/Library/Caches/Homebrew"
 HOMEBREW_PREFIX=Pathname.new(__FILE__).dirname.parent.parent.realpath
diff --git a/Library/Homebrew/hw.model.c b/Library/Homebrew/hw.model.c
new file mode 100644
index 0000000000..12436057b8
--- /dev/null
+++ b/Library/Homebrew/hw.model.c
@@ -0,0 +1,12 @@
+#include <sys/sysctl.h>
+#include <stdio.h>
+
+int main()
+{
+    char buf[32];
+    size_t sz = sizeof(buf);
+    int r = sysctlbyname("hw.model", buf, &sz, NULL, 0);
+    if (r == 0) 
+        printf("%.*s", sz, buf);
+    return r;
+}
diff --git a/Library/Homebrew/hw.model.rb b/Library/Homebrew/hw.model.rb
new file mode 100644
index 0000000000..87e6a6b3c7
--- /dev/null
+++ b/Library/Homebrew/hw.model.rb
@@ -0,0 +1,82 @@
+def hw_model_output
+  exe=Pathname.new(HOMEBREW_CACHE)+'hw.model'
+  Kernel.system "gcc -Os #{File.dirname __FILE__}/hw.model.c -o #{exe}" unless exe.file?
+  /(.*)(\d+),(\d+)/ =~ `#{exe}`
+  yield $1, $2.to_i, $3.to_i
+end
+
+# http://support.apple.com/kb/HT3696
+# http://www.cocoadev.com/index.pl?MacintoshModels
+def hw_model
+  hw_model_output do |model, major, minor|
+    case model
+      when "iMac" 
+        if major <=4
+          :core1
+        elsif major <=8
+          :core2
+        else
+          $unknown_hw_model=true
+          :core2
+        end
+
+      when "MacBookAir"
+        if major <= 1
+          :core2
+        else
+          $unknown_hw_model=true
+          :core2
+        end
+
+      when "MacBook"
+        if major <= 1
+          :core1
+        elsif major <= 4
+          :core2
+        else
+          $unknown_hw_model=true
+          :core2
+        end
+      
+      when "MacBookPro"
+        if major <= 1
+          :core1
+        elsif major <= 5
+          :core2
+        else
+          $unknown_hw_model=true
+          :core2
+        end
+      
+      when "Macmini" # Mac mini (Core Duo/Solo)
+        if major <= 1
+          :core
+        else
+          $unknown_hw_model=true
+          :core
+        end
+        
+      when "MacPro"
+        if major <= 3
+          :xeon
+        else
+          $unknown_hw_model=true
+          :xeon
+        end
+
+      when "PowerBook", "PowerMac", "RackMac" then :ppc
+
+      when "Xserve"
+        if major <=2
+          :xeon
+        else
+          $unknown_hw_model=true
+          :xeon
+        end
+        
+      when "ADP" then :dunno # Developer Transition Kit
+      when "M43ADP" then :dunno # Development Mac Pro
+      else :dunno
+    end
+  end
+end