diff --git a/nixos/lib/testing.nix b/nixos/lib/testing.nix
index 3407229e921..d5338bc04ca 100644
--- a/nixos/lib/testing.nix
+++ b/nixos/lib/testing.nix
@@ -67,62 +67,16 @@ rec {
     };
 
 
-  # Generate a coverage report from the coverage data produced by
-  # runTests.
-  makeReport = x: runCommand "report" { buildInputs = [rsync]; }
-    ''
-      mkdir -p $TMPDIR/gcov/
-
-      for d in ${x}/coverage-data/*; do
-          echo "doing $d"
-          [ -n "$(ls -A "$d")" ] || continue
-
-          for i in $(cd $d/nix/store && ls); do
-              if ! test -e $TMPDIR/gcov/nix/store/$i; then
-                  echo "copying $i"
-                  mkdir -p $TMPDIR/gcov/$(echo $i | cut -c34-)
-                  rsync -rv /nix/store/$i/.build/* $TMPDIR/gcov/
-              fi
-          done
-
-          chmod -R u+w $TMPDIR/gcov
-
-          find $TMPDIR/gcov -name "*.gcda" -exec rm {} \;
-
-          for i in $(cd $d/nix/store && ls); do
-              rsync -rv $d/nix/store/$i/.build/* $TMPDIR/gcov/
-          done
-
-          find $TMPDIR/gcov -name "*.gcda" -exec chmod 644 {} \;
-
-          echo "producing info..."
-          ${pkgs.lcov}/bin/geninfo --ignore-errors source,gcov $TMPDIR/gcov --output-file $TMPDIR/app.info
-          cat $TMPDIR/app.info >> $TMPDIR/full.info
-      done
-
-      echo "making report..."
-      mkdir -p $out/coverage
-      ${pkgs.lcov}/bin/genhtml --show-details $TMPDIR/full.info -o $out/coverage
-      cp $TMPDIR/full.info $out/coverage/
-
-      mkdir -p $out/nix-support
-      cat ${x}/nix-support/hydra-build-products >> $out/nix-support/hydra-build-products
-      echo "report coverage $out/coverage" >> $out/nix-support/hydra-build-products
-      [ ! -e ${x}/nix-support/failed ] || touch $out/nix-support/failed
-    ''; # */
-
-
   makeTest = testFun: complete (call testFun);
   makeTests = testsFun: lib.mapAttrs (name: complete) (call testsFun);
 
   apply = makeTest; # compatibility
   call = f: f { inherit pkgs system; };
 
-  complete = t: t // rec {
+  complete = { testScript, ... } @ t: t // rec {
+
     nodes = buildVirtualNetwork (
-      if t ? nodes then t.nodes else
-      if t ? machine then { machine = t.machine; }
-      else { } );
+      t.nodes or (if t ? machine then { machine = t.machine; } else { }));
 
     testScript =
       # Call the test script with the computed nodes.
@@ -162,7 +116,7 @@ rec {
 
     test = runTests driver;
 
-    report = makeReport test;
+    report = releaseTools.gcovReport { coverageRuns = [ test ]; };
   };
 
 
diff --git a/nixos/release.nix b/nixos/release.nix
index ff094cce05f..b98976c2cce 100644
--- a/nixos/release.nix
+++ b/nixos/release.nix
@@ -213,7 +213,8 @@ in rec {
     with lib;
     let
       testsFor = system:
-        mapAttrsRecursiveCond (x: !x ? test) (n: v: listToAttrs [(nameValuePair system v.test)])
+        mapAttrsRecursiveCond (x: !x ? test)
+          (n: v: listToAttrs [(nameValuePair system (if v.makeCoverageReport or false then v.report else v.test))])
           (import ./tests { inherit nixpkgs system; });
     in fold recursiveUpdate {} (map testsFor systems);
 }
diff --git a/nixos/tests/quake3.nix b/nixos/tests/quake3.nix
index 92501107780..fefbd75b4a3 100644
--- a/nixos/tests/quake3.nix
+++ b/nixos/tests/quake3.nix
@@ -14,11 +14,13 @@ in
 
 rec {
 
+  makeCoverageReport = true;
+
   client =
     { config, pkgs, ... }:
 
     { imports = [ ./common/x11.nix ];
-      services.xserver.driSupport = true;
+      hardware.opengl.driSupport = true;
       services.xserver.defaultDepth = pkgs.lib.mkOverride 0 16;
       environment.systemPackages = [ pkgs.quake3demo ];
       nixpkgs.config.packageOverrides = overrides;
diff --git a/nixos/tests/subversion.nix b/nixos/tests/subversion.nix
index 309da90c5df..49450c78f3b 100644
--- a/nixos/tests/subversion.nix
+++ b/nixos/tests/subversion.nix
@@ -20,7 +20,7 @@ let
         # To build the kernel with coverage instrumentation, we need a
         # special patch to make coverage data available under /proc.
         linux = pkgs.linux.override (orig: {
-          stdenv = cleanupBuildTree (keepBuildTree orig.stdenv);
+          stdenv = overrideInStdenv pkgs.stdenv [ pkgs.keepBuildTree ];
           extraConfig =
             ''
               GCOV_KERNEL y
diff --git a/pkgs/build-support/release/default.nix b/pkgs/build-support/release/default.nix
index acad3487dad..6288935ec2a 100644
--- a/pkgs/build-support/release/default.nix
+++ b/pkgs/build-support/release/default.nix
@@ -27,10 +27,14 @@ rec {
     } // args);
 
   coverageAnalysis = args: nixBuild (
-    { inherit lcov enableCoverageInstrumentation makeCoverageAnalysisReport;
+    { inherit lcov enableGCOVInstrumentation makeGCOVReport;
       doCoverageAnalysis = true;
     } // args);
 
+  gcovReport = args: import ./gcov-report.nix (
+    { inherit runCommand lcov rsync;
+    } // args);
+
   rpmBuild = args: import ./rpm-build.nix (
     { inherit vmTools;
     } // args);
diff --git a/pkgs/build-support/release/gcov-report.nix b/pkgs/build-support/release/gcov-report.nix
new file mode 100644
index 00000000000..8ce5c0488a7
--- /dev/null
+++ b/pkgs/build-support/release/gcov-report.nix
@@ -0,0 +1,49 @@
+{ runCommand, lcov, rsync, coverageRuns, lcovFilter ? [ "/nix/store/*" ], baseDirHack ? false }:
+
+runCommand "coverage"
+  { buildInputs = [ lcov rsync ];
+    inherit lcovFilter baseDirHack;
+  }
+  ''
+    mkdir -p $TMPDIR/gcov $out/nix-support $out/coverage
+    info=$out/coverage/full.info
+
+    for p in ${toString coverageRuns}; do
+        if [ -f $p/nix-support/hydra-build-products ]; then
+            cat $p/nix-support/hydra-build-products >> $out/nix-support/hydra-build-products
+        fi
+
+        [ ! -e $p/nix-support/failed ] || touch $out/nix-support/failed
+
+        opts=
+        for d in $p/coverage-data/*; do
+            for i in $(cd $d/nix/store && ls); do
+                if ! [ -e /nix/store/$i/.build ]; then continue; fi
+                if [ -e $TMPDIR/gcov/nix/store/$i ]; then continue; fi
+                echo "copying $i..."
+                rsync -a /nix/store/$i/.build/* $TMPDIR/gcov/
+                if [ -n "$baseDirHack" ]; then
+                    opts="-b $TMPDIR/gcov/$(cd /nix/store/$i/.build && ls)"
+                fi
+            done
+
+            for i in $(cd $d/nix/store && ls); do
+                rsync -a $d/nix/store/$i/.build/* $TMPDIR/gcov/ --include '*/' --include '*.gcda' --exclude '*'
+            done
+        done
+
+        chmod -R u+w $TMPDIR/gcov
+
+        echo "producing info..."
+        geninfo --ignore-errors source,gcov $TMPDIR/gcov --output-file $TMPDIR/app.info $opts
+        cat $TMPDIR/app.info >> $info
+    done
+
+    echo "making report..."
+    set -o noglob
+    lcov --remove $info ''$lcovFilter > $info.tmp
+    set +o noglob
+    mv $info.tmp $info
+    genhtml --show-details $info -o $out/coverage
+    echo "report coverage $out/coverage" >> $out/nix-support/hydra-build-products
+  ''
diff --git a/pkgs/build-support/release/nix-build.nix b/pkgs/build-support/release/nix-build.nix
index 993f12bc300..8ebae24c673 100644
--- a/pkgs/build-support/release/nix-build.nix
+++ b/pkgs/build-support/release/nix-build.nix
@@ -79,7 +79,7 @@ stdenv.mkDerivation (
 
     prePhases = ["initPhase"] ++ prePhases;
 
-    buildInputs = buildInputs ++ stdenv.lib.optional doCoverageAnalysis args.makeCoverageAnalysisReport;
+    buildInputs = buildInputs ++ stdenv.lib.optional doCoverageAnalysis args.makeGCOVReport;
 
     lcovFilter = ["/nix/store/*"] ++ lcovFilter;
 
diff --git a/pkgs/build-support/setup-hooks/enable-coverage-instrumentation.sh b/pkgs/build-support/setup-hooks/enable-coverage-instrumentation.sh
index 08ef490e244..7175b408b02 100644
--- a/pkgs/build-support/setup-hooks/enable-coverage-instrumentation.sh
+++ b/pkgs/build-support/setup-hooks/enable-coverage-instrumentation.sh
@@ -1,3 +1,5 @@
+postPhases+=" cleanupBuildDir"
+
 # Force GCC to build with coverage instrumentation.  Also disable
 # optimisation, since it may confuse things.
 export NIX_CFLAGS_COMPILE="$NIX_CFLAGS_COMPILE -O0 --coverage"
@@ -12,3 +14,18 @@ postUnpack() {
         substituteInPlace $i --replace '*.$objext)' '*.$objext | *.gcno)'
     done
 }
+
+# Get rid of everything that isn't a gcno file or a C source file.
+# Also strip the `.tmp_' prefix from gcno files.  (The Linux kernel
+# creates these.)
+cleanupBuildDir() {
+    if ! [ -e $out/.build ]; then return; fi
+
+    find $out/.build/ -type f -a ! \
+        \( -name "*.c" -o -name "*.cc" -o -name "*.cpp" -o -name "*.h" -o -name "*.hh" -o -name "*.y" -o -name "*.l" -o -name "*.gcno" \) \
+        | xargs rm -f --
+
+    for i in $(find $out/.build/ -name ".tmp_*.gcno"); do
+        mv "$i" "$(echo $i | sed s/.tmp_//)"
+    done
+}
diff --git a/pkgs/build-support/setup-hooks/keep-build-tree.sh b/pkgs/build-support/setup-hooks/keep-build-tree.sh
new file mode 100644
index 00000000000..754900bfc33
--- /dev/null
+++ b/pkgs/build-support/setup-hooks/keep-build-tree.sh
@@ -0,0 +1,6 @@
+prePhases+=" moveBuildDir"
+
+moveBuildDir() {
+    mkdir -p $out/.build
+    cd $out/.build
+}
diff --git a/pkgs/stdenv/adapters.nix b/pkgs/stdenv/adapters.nix
index cb7e3ba925f..0e45ad05531 100644
--- a/pkgs/stdenv/adapters.nix
+++ b/pkgs/stdenv/adapters.nix
@@ -187,51 +187,13 @@ rec {
     { mkDerivation = args: stdenv.mkDerivation (args // extraAttrs); };
 
 
-  /* Return a modified stdenv that performs the build under $out/.build
-     instead of in $TMPDIR.  Thus, the sources are kept available.
-     This is useful for things like debugging or generation of
-     dynamic analysis reports. */
-  keepBuildTree = stdenv:
-    addAttrsToDerivation
-      { prePhases = "moveBuildDir";
-
-        moveBuildDir =
-          ''
-            mkdir -p $out/.build
-            cd $out/.build
-          '';
-      } stdenv;
-
-
-  cleanupBuildTree = stdenv:
-    addAttrsToDerivation
-      { postPhases = "cleanupBuildDir";
-
-        # Get rid of everything that isn't a gcno file or a C source
-        # file.  This also includes the gcda files; we're not
-        # interested in coverage resulting from the package's own test
-        # suite.  Also strip the `.tmp_' prefix from gcno files.  (The
-        # Linux kernel creates these.)
-        cleanupBuildDir =
-          ''
-            find $out/.build/ -type f -a ! \
-              \( -name "*.c" -o -name "*.h" -o -name "*.gcno" \) \
-              | xargs rm -f --
-
-            for i in $(find $out/.build/ -name ".tmp_*.gcno"); do
-                mv "$i" "$(echo $i | sed s/.tmp_//)"
-            done
-          '';
-      } stdenv;
-
-
   /* Return a modified stdenv that builds packages with GCC's coverage
      instrumentation.  The coverage note files (*.gcno) are stored in
      $out/.build, along with the source code of the package, to enable
      programs like lcov to produce pretty-printed reports.
   */
   addCoverageInstrumentation = stdenv:
-    cleanupBuildTree (keepBuildTree (overrideInStdenv stdenv [ pkgs.enableCoverageInstrumentation ]));
+    overrideInStdenv stdenv [ pkgs.enableGCOVInstrumentation pkgs.keepBuildTree ];
 
 
   /* Replace the meta.maintainers field of a derivation.  This is useful
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 0d22468e5ec..a79317cd6ba 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -396,10 +396,12 @@ let
 
   fixDarwinDylibNames = makeSetupHook { } ../build-support/setup-hooks/fix-darwin-dylib-names.sh;
 
-  enableCoverageInstrumentation = makeSetupHook { } ../build-support/setup-hooks/enable-coverage-instrumentation.sh;
+  keepBuildTree = makeSetupHook { } ../build-support/setup-hooks/keep-build-tree.sh;
 
-  makeCoverageAnalysisReport = makeSetupHook
-    { deps = [ pkgs.lcov pkgs.enableCoverageInstrumentation ]; }
+  enableGCOVInstrumentation = makeSetupHook { } ../build-support/setup-hooks/enable-coverage-instrumentation.sh;
+
+  makeGCOVReport = makeSetupHook
+    { deps = [ pkgs.lcov pkgs.enableGCOVInstrumentation ]; }
     ../build-support/setup-hooks/make-coverage-analysis-report.sh;