diff --git a/pkgs/development/compilers/llvm/3.4/llvm.nix b/pkgs/development/compilers/llvm/3.4/llvm.nix
index dfd7b5570eae5..f7f794f4f87b3 100644
--- a/pkgs/development/compilers/llvm/3.4/llvm.nix
+++ b/pkgs/development/compilers/llvm/3.4/llvm.nix
@@ -65,6 +65,5 @@ in stdenv.mkDerivation rec {
     license     = stdenv.lib.licenses.bsd3;
     maintainers = with stdenv.lib.maintainers; [ shlevy lovek323 raskin viric ];
     platforms   = stdenv.lib.platforms.all;
-    # broken      = stdenv.isDarwin;
   };
 }
diff --git a/pkgs/development/compilers/ocaml/4.01.0.nix b/pkgs/development/compilers/ocaml/4.01.0.nix
index 0f68014fad643..a2138d0b835ba 100644
--- a/pkgs/development/compilers/ocaml/4.01.0.nix
+++ b/pkgs/development/compilers/ocaml/4.01.0.nix
@@ -26,6 +26,8 @@ stdenv.mkDerivation rec {
     sha256 = "b1ca708994180236917ae79e17606da5bd334ca6acd6873a550027e1c0ec874a";
   };
 
+  patches = [ ./fix-clang-build-on-osx.diff ];
+
   prefixKey = "-prefix ";
   configureFlags = ["-no-tk"] ++ optionals useX11 [ "-x11lib" x11lib
                                                     "-x11include" x11inc ];
diff --git a/pkgs/development/compilers/ocaml/fix-clang-build-on-osx.diff b/pkgs/development/compilers/ocaml/fix-clang-build-on-osx.diff
new file mode 100644
index 0000000000000..d7d9c863858f1
--- /dev/null
+++ b/pkgs/development/compilers/ocaml/fix-clang-build-on-osx.diff
@@ -0,0 +1,20 @@
+diff --git a/configure b/configure
+index d45e88f..25d872b 100755
+--- a/configure
++++ b/configure
+@@ -322,7 +322,14 @@ case "$bytecc,$target" in
+     bytecccompopts="-fno-defer-pop $gcc_warnings -DSHRINKED_GNUC"
+     mathlib="";;
+   *,*-*-darwin*)
+-    bytecccompopts="-fno-defer-pop $gcc_warnings"
++    # On recent version of OSX, gcc is a symlink to clang
++    if $bytecc --version | grep -q clang; then
++        # -fno-defer-pop is not supported by clang, and make recent
++        # versions of clang to fail
++        bytecccompopts="$gcc_warnings"
++    else
++        bytecccompopts="-fno-defer-pop $gcc_warnings"
++    fi
+     mathlib=""
+     mkexe="$mkexe -Wl,-no_compact_unwind"
+     # Tell gcc that we can use 32-bit code addresses for threaded code
diff --git a/pkgs/development/libraries/boost/1.55.nix b/pkgs/development/libraries/boost/1.55.nix
index bf355f7169c6b..bddcbcfc070ba 100644
--- a/pkgs/development/libraries/boost/1.55.nix
+++ b/pkgs/development/libraries/boost/1.55.nix
@@ -1,5 +1,5 @@
 { stdenv, fetchurl, icu, expat, zlib, bzip2, python, fixDarwinDylibNames
-, toolset ? null
+, toolset ? if stdenv.isDarwin then "clang" else null
 , enableRelease ? true
 , enableDebug ? false
 , enableSingleThreaded ? false
@@ -57,6 +57,8 @@ stdenv.mkDerivation {
     sha256 = "0lkv5dzssbl5fmh2nkaszi8x9qbj80pr4acf9i26sj3rvlih1w7z";
   };
 
+  patches = stdenv.lib.optional (toolset == "clang") [ ./boost-155-clang.patch ];
+
   enableParallelBuilding = true;
 
   buildInputs =
@@ -66,7 +68,7 @@ stdenv.mkDerivation {
   configureScript = "./bootstrap.sh";
   configureFlags = "--with-icu=${icu} --with-python=${python}/bin/python" + withToolset;
 
-  buildPhase = "${stdenv.lib.optionalString (toolset == "clang") "unset NIX_ENFORCE_PURITY; "}./b2 -j$NIX_BUILD_CORES -sEXPAT_INCLUDE=${expat}/include -sEXPAT_LIBPATH=${expat}/lib --layout=${layout} variant=${variant} threading=${threading} link=${link} ${cflags} install${withToolset}";
+  buildPhase = "${stdenv.lib.optionalString (toolset == "clang") "unset NIX_ENFORCE_PURITY; "}./b2 -j$NIX_BUILD_CORES -sEXPAT_INCLUDE=${expat}/include -sEXPAT_LIBPATH=${expat}/lib --layout=${layout} variant=${variant} threading=${threading} link=${link} ${cflags} install";
 
   # normal install does not install bjam, this is a separate step
   installPhase = ''
diff --git a/pkgs/development/libraries/boost/boost-155-clang.patch b/pkgs/development/libraries/boost/boost-155-clang.patch
new file mode 100644
index 0000000000000..9c4e3a74cd256
--- /dev/null
+++ b/pkgs/development/libraries/boost/boost-155-clang.patch
@@ -0,0 +1,90 @@
+diff --git a/boost/atomic/detail/cas128strong.hpp b/boost/atomic/detail/cas128strong.hpp
+index 906c13e..dcb4d7d 100644
+--- a/boost/atomic/detail/cas128strong.hpp
++++ b/boost/atomic/detail/cas128strong.hpp
+@@ -196,15 +196,17 @@ class base_atomic<T, void, 16, Sign>
+ 
+ public:
+     BOOST_DEFAULTED_FUNCTION(base_atomic(void), {})
+-    explicit base_atomic(value_type const& v) BOOST_NOEXCEPT : v_(0)
++    explicit base_atomic(value_type const& v) BOOST_NOEXCEPT
+     {
++        memset(&v_, 0, sizeof(v_));
+         memcpy(&v_, &v, sizeof(value_type));
+     }
+ 
+     void
+     store(value_type const& value, memory_order order = memory_order_seq_cst) volatile BOOST_NOEXCEPT
+     {
+-        storage_type value_s = 0;
++        storage_type value_s;
++        memset(&value_s, 0, sizeof(value_s));
+         memcpy(&value_s, &value, sizeof(value_type));
+         platform_fence_before_store(order);
+         platform_store128(value_s, &v_);
+@@ -247,7 +249,9 @@ class base_atomic<T, void, 16, Sign>
+         memory_order success_order,
+         memory_order failure_order) volatile BOOST_NOEXCEPT
+     {
+-        storage_type expected_s = 0, desired_s = 0;
++        storage_type expected_s, desired_s;
++        memset(&expected_s, 0, sizeof(expected_s));
++        memset(&desired_s, 0, sizeof(desired_s));
+         memcpy(&expected_s, &expected, sizeof(value_type));
+         memcpy(&desired_s, &desired, sizeof(value_type));
+
+diff --git a/boost/atomic/detail/gcc-atomic.hpp b/boost/atomic/detail/gcc-atomic.hpp
+index a130590..4af99a1 100644
+--- a/boost/atomic/detail/gcc-atomic.hpp
++++ b/boost/atomic/detail/gcc-atomic.hpp
+@@ -958,14 +958,16 @@ class base_atomic<T, void, 16, Sign>
+ 
+ public:
+     BOOST_DEFAULTED_FUNCTION(base_atomic(void), {})
+-    explicit base_atomic(value_type const& v) BOOST_NOEXCEPT : v_(0)
++    explicit base_atomic(value_type const& v) BOOST_NOEXCEPT
+     {
++        memset(&v_, 0, sizeof(v_));
+         memcpy(&v_, &v, sizeof(value_type));
+     }
+ 
+     void store(value_type const& v, memory_order order = memory_order_seq_cst) volatile BOOST_NOEXCEPT
+     {
+-        storage_type tmp = 0;
++        storage_type tmp;
++        memset(&tmp, 0, sizeof(tmp));
+         memcpy(&tmp, &v, sizeof(value_type));
+         __atomic_store_n(&v_, tmp, atomics::detail::convert_memory_order_to_gcc(order));
+     }
+@@ -980,7 +982,8 @@ class base_atomic<T, void, 16, Sign>
+ 
+     value_type exchange(value_type const& v, memory_order order = memory_order_seq_cst) volatile BOOST_NOEXCEPT
+     {
+-        storage_type tmp = 0;
++        storage_type tmp;
++        memset(&tmp, 0, sizeof(tmp));
+         memcpy(&tmp, &v, sizeof(value_type));
+         tmp = __atomic_exchange_n(&v_, tmp, atomics::detail::convert_memory_order_to_gcc(order));
+         value_type res;
+@@ -994,7 +997,9 @@ class base_atomic<T, void, 16, Sign>
+         memory_order success_order,
+         memory_order failure_order) volatile BOOST_NOEXCEPT
+     {
+-        storage_type expected_s = 0, desired_s = 0;
++        storage_type expected_s, desired_s;
++        memset(&expected_s, 0, sizeof(expected_s));
++        memset(&desired_s, 0, sizeof(desired_s));
+         memcpy(&expected_s, &expected, sizeof(value_type));
+         memcpy(&desired_s, &desired, sizeof(value_type));
+         const bool success = __atomic_compare_exchange_n(&v_, &expected_s, desired_s, false,
+@@ -1010,7 +1015,9 @@ class base_atomic<T, void, 16, Sign>
+         memory_order success_order,
+         memory_order failure_order) volatile BOOST_NOEXCEPT
+     {
+-        storage_type expected_s = 0, desired_s = 0;
++        storage_type expected_s, desired_s;
++        memset(&expected_s, 0, sizeof(expected_s));
++        memset(&desired_s, 0, sizeof(desired_s));
+         memcpy(&expected_s, &expected, sizeof(value_type));
+         memcpy(&desired_s, &desired, sizeof(value_type));
+         const bool success = __atomic_compare_exchange_n(&v_, &expected_s, desired_s, true,
diff --git a/pkgs/development/libraries/libc++abi/default.nix b/pkgs/development/libraries/libc++abi/default.nix
index cedd4bc6dba48..4020856575b5e 100644
--- a/pkgs/development/libraries/libc++abi/default.nix
+++ b/pkgs/development/libraries/libc++abi/default.nix
@@ -1,4 +1,4 @@
-{ stdenv, fetchsvn, libcxx, libunwind, gnused }:
+{ stdenv, coreutils, fetchsvn, libcxx, libunwind, gnused }:
 let
   rev = "199626";
 in stdenv.mkDerivation {
@@ -12,6 +12,8 @@ in stdenv.mkDerivation {
 
   NIX_CFLAGS_LINK="-L${libunwind}/lib -lunwind";
 
+  buildInputs = [ coreutils ];
+
   postUnpack = ''
     unpackFile ${libcxx.src}
     export NIX_CFLAGS_COMPILE="-I${libunwind}/include -I$PWD/include -I$(readlink -f libcxx-*)/include"
diff --git a/pkgs/development/tools/misc/sloccount/default.nix b/pkgs/development/tools/misc/sloccount/default.nix
index 455305be74922..9ed55259af29b 100644
--- a/pkgs/development/tools/misc/sloccount/default.nix
+++ b/pkgs/development/tools/misc/sloccount/default.nix
@@ -31,6 +31,7 @@ stdenv.mkDerivation rec {
 
   configurePhase = ''
     sed -i "makefile" -"es|PREFIX[[:blank:]]*=.*$|PREFIX = $out|g"
+    sed -i "makefile" -"es|gcc|$CC|g"
   '';
 
   doCheck = true;
diff --git a/pkgs/shells/fish/default.nix b/pkgs/shells/fish/default.nix
index adfe44b3bac1d..03ecc290d14ca 100644
--- a/pkgs/shells/fish/default.nix
+++ b/pkgs/shells/fish/default.nix
@@ -31,7 +31,7 @@ stdenv.mkDerivation rec {
     description = "Smart and user-friendly command line shell";
     homepage = "http://fishshell.com/";
     license = licenses.gpl2;
-    platforms = platforms.linux;
+    platforms = platforms.unix;
     maintainers = with maintainers; [ ocharles ];
   };
 }
diff --git a/pkgs/tools/compression/bzip2/default.nix b/pkgs/tools/compression/bzip2/default.nix
index 55fca6ca3cb9d..256f574c2e0c5 100644
--- a/pkgs/tools/compression/bzip2/default.nix
+++ b/pkgs/tools/compression/bzip2/default.nix
@@ -26,6 +26,8 @@ stdenv.mkDerivation {
   sharedLibrary =
     !stdenv.isDarwin && !(stdenv ? isDietLibC) && !(stdenv ? isStatic) && stdenv.system != "i686-cygwin" && !linkStatic;
 
+  patchPhase = stdenv.lib.optionalString stdenv.isDarwin "substituteInPlace Makefile --replace 'CC=gcc' 'CC=clang'";
+
   preConfigure = "substituteInPlace Makefile --replace '$(PREFIX)/man' '$(PREFIX)/share/man'";
 
   makeFlags = if linkStatic then "LDFLAGS=-static" else "";
diff --git a/pkgs/tools/networking/isync/default.nix b/pkgs/tools/networking/isync/default.nix
index 2d3ffb2cb0a8c..021f470af241b 100644
--- a/pkgs/tools/networking/isync/default.nix
+++ b/pkgs/tools/networking/isync/default.nix
@@ -16,6 +16,6 @@ stdenv.mkDerivation rec {
     license = [ "GPLv2+" ];
 
     maintainers = with stdenv.lib.maintainers; [ the-kenny viric ];
-    platforms = stdenv.lib.platforms.linux;
+    platforms = stdenv.lib.platforms.unix;
   };
 }
diff --git a/pkgs/tools/typesetting/tex/tex4ht/default.nix b/pkgs/tools/typesetting/tex/tex4ht/default.nix
index 69d02a275b341..93d33439084a4 100644
--- a/pkgs/tools/typesetting/tex/tex4ht/default.nix
+++ b/pkgs/tools/typesetting/tex/tex4ht/default.nix
@@ -14,7 +14,7 @@ stdenv.mkDerivation rec {
     cd src
     for f in tex4ht t4ht htcmd ; do
       # -DENVFILE="$out/share/texmf-nix/tex4ht/base/unix/tex4ht.env"
-      gcc -o $f $f.c -I${tetex}/include -L${tetex}/lib  -DHAVE_DIRENT_H -DHAVE_DIRENT_H -DKPATHSEA -lkpathsea
+      $CC -o $f $f.c -I${tetex}/include -L${tetex}/lib  -DHAVE_DIRENT_H -DHAVE_DIRENT_H -DKPATHSEA -lkpathsea
     done
     cd -
   '';
diff --git a/pkgs/tools/typesetting/tex/texlive/default.nix b/pkgs/tools/typesetting/tex/texlive/default.nix
index c2840fd843ff8..b5589cf943b36 100644
--- a/pkgs/tools/typesetting/tex/texlive/default.nix
+++ b/pkgs/tools/typesetting/tex/texlive/default.nix
@@ -22,7 +22,6 @@ rec {
   setupHook = ./setup-hook.sh;
 
   doMainBuild = fullDepEntry ( stdenv.lib.optionalString stdenv.isDarwin ''
-    export MACOSX_DEPLOYMENT_TARGET=10.9
     export DYLD_LIBRARY_PATH="${poppler}/lib"
   '' + ''
     mkdir -p $out