diff --git a/artiq/default.nix b/artiq/default.nix
index 72959da..e886353 100644
--- a/artiq/default.nix
+++ b/artiq/default.nix
@@ -3,8 +3,6 @@ with pkgs;
 let
   pythonDeps = callPackage ./pkgs/python-deps.nix {};
 
-  llvm-src = callPackage ./fetch-llvm-clang.nix {};
-
   boards = [
     { target = "kasli"; variant = "tester"; }
     { target = "kc705"; variant = "nist_clock"; }
@@ -33,7 +31,7 @@ in
   rec {
     inherit (pythonDeps) asyncserial levenshtein pythonparser quamash pyqtgraph-qt5 misoc migen microscope jesd204b lit outputcheck sphinx-argparse wavedrom sphinxcontrib-wavedrom;
     binutils-or1k = callPackage ./pkgs/binutils-or1k.nix {};
-    llvm-or1k = callPackage ./pkgs/llvm-or1k.nix { inherit llvm-src; };
+    llvm-or1k = callPackage ./pkgs/llvm-or1k.nix {};
     rustc = callPackage ./pkgs/rust
       ((stdenv.lib.optionalAttrs (stdenv.cc.isGNU && stdenv.hostPlatform.isi686) {
          stdenv = overrideCC stdenv gcc6; # with gcc-7: undefined reference to `__divmoddi4'
diff --git a/artiq/pkgs/llvm-or1k.nix b/artiq/pkgs/llvm-or1k.nix
index 744a384..396dda8 100644
--- a/artiq/pkgs/llvm-or1k.nix
+++ b/artiq/pkgs/llvm-or1k.nix
@@ -1,45 +1,64 @@
 { stdenv
-, git
-, llvm-src
-,  perl, groff, cmake, libxml2, python, libffi, valgrind
-, ...
+, fetchFromGitHub, runCommand
+, perl, groff, cmake, libxml2, python, libffi, valgrind
 }:
 
-stdenv.mkDerivation rec {
-  name = "llvm_or1k";
-  src = llvm-src;
-
- buildInputs = [ perl groff cmake libxml2 python libffi ] ++ stdenv.lib.optional stdenv.isLinux valgrind;
-
-  preBuild = ''
-    NIX_BUILD_CORES=4
-    makeFlagsArray=(-j''$NIX_BUILD_CORES)
-    mkdir -p $out/
-  '';
-
-  cmakeFlags = with stdenv; [
-    "-DCMAKE_BUILD_TYPE=Release"
-    "-DLLVM_BUILD_LLVM_DYLIB=ON"
-    "-DLLVM_LINK_LLVM_DYLIB=ON"
-    "-DLLVM_TARGETS_TO_BUILD=X86"
-    "-DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD=OR1K"
-    "-DLLVM_ENABLE_ASSERTIONS=OFF"
-    "-DLLVM_INSTALL_UTILS=ON"
-    "-DLLVM_INCLUDE_TESTS=OFF"
-    "-DLLVM_INCLUDE_DOCS=OFF"
-    "-DLLVM_INCLUDE_EXAMPLES=OFF"
-    "-DCLANG_ENABLE_ARCMT=OFF"
-    "-DCLANG_ENABLE_STATIC_ANALYZER=OFF"
-    "-DCLANG_INCLUDE_TESTS=OFF"
-    "-DCLANG_INCLUDE_DOCS=OFF"
-  ];
-
-  enableParallelBuilding = true;
-  meta = {
-    description = "Collection of modular and reusable compiler and toolchain technologies";
-    homepage = http://llvm.org/;
-    license = stdenv.lib.licenses.bsd3;
-    maintainers = with stdenv.lib.maintainers; [ sb0 ];
-    platforms = stdenv.lib.platforms.all;
+let
+  llvm-src = fetchFromGitHub {
+    rev = "527aa86b578da5dfb9cf4510b71f0f46a11249f7";
+    owner = "m-labs";
+    repo = "llvm-or1k";
+    sha256 = "0lmcg9xj66pf4mb6racipw67vm8kwm84dl861hyqnywd61kvhrwa";
   };
-}
+  clang-src = fetchFromGitHub {
+    rev = "9e996136d52ed506ed8f57ef8b13b0f0f735e6a3";
+    owner = "m-labs";
+    repo = "clang-or1k";
+    sha256 = "0w5f450i76y162aswi2c7jip8x3arzljaxhbqp8qfdffm0rdbjp4";
+  };
+  llvm-clang-src = runCommand "llvm-clang-src" {}
+    ''
+    mkdir -p $out
+    mkdir -p $out/tools/clang
+    cp -r ${llvm-src}/* $out/
+    cp -r ${clang-src}/* $out/tools/clang
+    '';
+in
+  stdenv.mkDerivation rec {
+    name = "llvm-or1k";
+    src = llvm-clang-src;
+
+   buildInputs = [ perl groff cmake libxml2 python libffi ] ++ stdenv.lib.optional stdenv.isLinux valgrind;
+
+    preBuild = ''
+      NIX_BUILD_CORES=4
+      makeFlagsArray=(-j''$NIX_BUILD_CORES)
+      mkdir -p $out/
+    '';
+
+    cmakeFlags = with stdenv; [
+      "-DCMAKE_BUILD_TYPE=Release"
+      "-DLLVM_BUILD_LLVM_DYLIB=ON"
+      "-DLLVM_LINK_LLVM_DYLIB=ON"
+      "-DLLVM_TARGETS_TO_BUILD=X86"
+      "-DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD=OR1K"
+      "-DLLVM_ENABLE_ASSERTIONS=OFF"
+      "-DLLVM_INSTALL_UTILS=ON"
+      "-DLLVM_INCLUDE_TESTS=OFF"
+      "-DLLVM_INCLUDE_DOCS=OFF"
+      "-DLLVM_INCLUDE_EXAMPLES=OFF"
+      "-DCLANG_ENABLE_ARCMT=OFF"
+      "-DCLANG_ENABLE_STATIC_ANALYZER=OFF"
+      "-DCLANG_INCLUDE_TESTS=OFF"
+      "-DCLANG_INCLUDE_DOCS=OFF"
+    ];
+
+    enableParallelBuilding = true;
+    meta = {
+      description = "Collection of modular and reusable compiler and toolchain technologies";
+      homepage = http://llvm.org/;
+      license = stdenv.lib.licenses.bsd3;
+      maintainers = with stdenv.lib.maintainers; [ sb0 ];
+      platforms = stdenv.lib.platforms.all;
+    };
+  }