Index: zorg/buildbot/builders/sanitizers/buildbot_bootstrap.sh
===================================================================
--- zorg/buildbot/builders/sanitizers/buildbot_bootstrap.sh
+++ zorg/buildbot/builders/sanitizers/buildbot_bootstrap.sh
@@ -23,7 +23,13 @@
 STAGE3_ASAN_DIR=llvm_build2_asan
 STAGE3_MSAN_DIR=llvm_build2_msan
 LLVM=$ROOT/llvm
-CMAKE_COMMON_OPTIONS="-GNinja -DCMAKE_BUILD_TYPE=Release -DLLVM_ENABLE_ASSERTIONS=ON -DLLVM_PARALLEL_LINK_JOBS=20"
+ZLIB=$ROOT/zlib
+CMAKE_COMMON_OPTIONS="-GNinja -DCMAKE_BUILD_TYPE=Release -DLLVM_ENABLE_ASSERTIONS=ON -DLLVM_PARALLEL_LINK_JOBS=10"
+
+function build_symbolizer {
+  check_stage2 msan "${STAGE2_MSAN_DIR}" @@@STEP_FAILURE@@@
+  (cd $1 && $LLVM/ninja check-llvm) || echo @@@STEP_FAILURE@@@
+}
 
 if [ "$BUILDBOT_CLOBBER" != "" ]; then
   echo @@@BUILD_STEP clobber@@@
@@ -34,18 +40,21 @@
 # CMake does not notice that the compiler itself has changed.
 # Anyway, incremental builds of stage2 and stage3 compilers don't make sense.
 # Clobber the build trees.
-rm -rf ${STAGE2_LIBCXX_MSAN_DIR}
-rm -rf ${STAGE2_LIBCXX_ASAN_DIR}
-rm -rf ${STAGE2_LIBCXX_UBSAN_DIR}
-rm -rf ${STAGE2_MSAN_DIR}
-rm -rf ${STAGE3_MSAN_DIR}
-rm -rf ${STAGE2_ASAN_DIR}
-rm -rf ${STAGE3_ASAN_DIR}
-rm -rf ${STAGE2_UBSAN_DIR}
+# rm -rf ${STAGE2_LIBCXX_MSAN_DIR}
+# rm -rf ${STAGE2_LIBCXX_ASAN_DIR}
+# rm -rf ${STAGE2_LIBCXX_UBSAN_DIR}
+# rm -rf ${STAGE2_MSAN_DIR}
+# rm -rf ${STAGE3_MSAN_DIR}
+# rm -rf ${STAGE2_ASAN_DIR}
+# rm -rf ${STAGE3_ASAN_DIR}
+# rm -rf ${STAGE2_UBSAN_DIR}
 
 echo @@@BUILD_STEP update@@@
 buildbot_update
 
+echo @@@BUILD_STEP update zlib@@@
+git -C $ZLIB pull --rebase || git clone  https://github.com/madler/zlib.git $ZLIB || echo @@@STEP_FAILURE@@@
+
 # Stage 1
 
 echo @@@BUILD_STEP build stage1 clang@@@
@@ -58,6 +67,12 @@
 
 check_stage2_msan
 
+build_symbolizer "${STAGE2_MSAN_DIR}"
+
+check_stage2_msan
+
+exit 1
+
 # Stage 3 / MemorySanitizer
 
 echo @@@BUILD_STEP build stage3/msan clang@@@
Index: zorg/buildbot/builders/sanitizers/buildbot_cmake.sh
===================================================================
--- zorg/buildbot/builders/sanitizers/buildbot_cmake.sh
+++ zorg/buildbot/builders/sanitizers/buildbot_cmake.sh
@@ -135,36 +135,22 @@
 # Do a sanity check on Linux: build and test sanitizers using gcc as a host
 # compiler.
 if [ "$PLATFORM" == "Linux" ]; then
-  echo @@@BUILD_STEP check-sanitizer in gcc build@@@
-  (cd clang_build && make -j$MAKE_JOBS check-sanitizer) || echo @@@STEP_FAILURE@@@
-  if [ "$CHECK_ASAN" == "1" ]; then
-    echo @@@BUILD_STEP check-asan in gcc build@@@
-    (cd clang_build && make -j$MAKE_JOBS check-asan) || echo @@@STEP_FAILURE@@@
-  fi
-  if [ "$CHECK_UBSAN" == "1" ]; then
-    echo @@@BUILD_STEP check-ubsan in gcc build@@@
-    (cd clang_build && make -j$MAKE_JOBS check-ubsan) || echo @@@STEP_FAILURE@@@
-  fi
-  if [ "$CHECK_LSAN" == "1" ]; then
-    echo @@@BUILD_STEP check-lsan in gcc build@@@
-    (cd clang_build && make -j$MAKE_JOBS check-lsan) || echo @@@STEP_FAILURE@@@
-  fi
-  if [ "$CHECK_MSAN" == "1" ]; then
-    echo @@@BUILD_STEP check-msan in gcc build@@@
-    (cd clang_build && make -j$MAKE_JOBS check-msan) || echo @@@STEP_FAILURE@@@
-  fi
-  if [ "$CHECK_TSAN" == "1" ]; then
-    echo @@@BUILD_STEP check-tsan in gcc build@@@
-    (cd clang_build && make -j$MAKE_JOBS check-tsan) || echo @@@STEP_FAILURE@@@
-  fi
-  if [ "$CHECK_DFSAN" == "1" ]; then
-    echo @@@BUILD_STEP check-dfsan in gcc build@@@
-    (cd clang_build && make -j$MAKE_JOBS check-dfsan) || echo @@@STEP_WARNINGS@@@
-  fi
-  if [ "$CHECK_CFI" == "1" ]; then
-    echo @@@BUILD_STEP check-cfi-and-supported in gcc build@@@
-    (cd clang_build && make -j$MAKE_JOBS check-cfi-and-supported) || echo @@@STEP_FAILURE@@@
-  fi
+  check_in_gcc() {
+    CONDITION=$1
+    SANITIZER=$2
+    if [ "$CONDITION" == "1" ]; then
+      echo @@@BUILD_STEP check-$SANITIZER in gcc build@@@
+      (cd clang_build && make -j$MAKE_JOBS check-$SANITIZER) || echo @@@STEP_FAILURE@@@
+    fi
+  }
+  check_in_gcc 1 sanitizer
+  check_in_gcc $CHECK_ASAN asan
+  check_in_gcc $CHECK_CFI cfi-and-supported
+  check_in_gcc $CHECK_DFSAN dfsan
+  check_in_gcc $CHECK_LSAN lsan
+  check_in_gcc $CHECK_MSAN msan
+  check_in_gcc $CHECK_TSAN tsan
+  check_in_gcc $CHECK_UBSAN ubsan
 fi
 
 ### From now on we use just-built Clang as a host compiler ###
@@ -191,44 +177,32 @@
 
 # Now build everything else.
 (cd llvm_build64 && make -j$MAKE_JOBS) || echo @@@STEP_FAILURE@@@
+# FIXME: Make these true dependencies of check-cfi-and-supported when
+  # compiler-rt is configured as an external project.
+(cd llvm_build64 && make -j$MAKE_JOBS LLVMgold opt sanstats) || echo @@@STEP_FAILURE@@@
+
 FRESH_CLANG_PATH=${ROOT}/llvm_build64/bin
 COMPILER_RT_BUILD_PATH=projects/compiler-rt/src/compiler-rt-build
 
-if [ "$CHECK_ASAN" == "1" ]; then
-  echo @@@BUILD_STEP run asan tests@@@
-  (cd llvm_build64 && make -j$MAKE_JOBS check-asan) || echo @@@STEP_FAILURE@@@
-fi
-
-if [ "$PLATFORM" == "Linux" -a "$CHECK_ASAN" == "1" ]; then
-  echo @@@BUILD_STEP run asan-dynamic tests@@@
-  (cd llvm_build64 && make -j$MAKE_JOBS check-asan-dynamic) || echo @@@STEP_FAILURE@@@
-fi
-
-if [ "$PLATFORM" == "Linux" -a "$CHECK_MSAN" == "1" ]; then
-  echo @@@BUILD_STEP run msan unit tests@@@
-  (cd llvm_build64 && make -j$MAKE_JOBS check-msan) || echo @@@STEP_FAILURE@@@
-fi
-
-if [ "$PLATFORM" == "Linux" -a "$CHECK_TSAN" == "1" ]; then
-  echo @@@BUILD_STEP run 64-bit tsan unit tests@@@
-  (cd llvm_build64 && make -j$MAKE_JOBS check-tsan) || echo @@@STEP_FAILURE@@@
-fi
-
-if [ "$PLATFORM" == "Linux" -a "$CHECK_LSAN" == "1" ]; then
-  echo @@@BUILD_STEP run 64-bit lsan unit tests@@@
-  (cd llvm_build64 && make -j$MAKE_JOBS check-lsan) || echo @@@STEP_FAILURE@@@
-fi
-
-if [ "$PLATFORM" == "Linux" -a "$CHECK_DFSAN" == "1" ]; then
-  echo @@@BUILD_STEP run 64-bit dfsan unit tests@@@
-  (cd llvm_build64 && make -j$MAKE_JOBS check-dfsan) || echo @@@STEP_FAILURE@@@
-fi
+check_64bit() {
+  CONDITION=$1
+  SANITIZER=$2
+  if ["$CONDITION" == "1" ]; then
+    echo @@@BUILD_STEP 64-bit check-$SANITIZER@@@
+    (cd llvm_build64 && make -j$MAKE_JOBS check-$SANITIZER) || echo @@@STEP_FAILURE@@@
+  fi
+}
 
-if [ "$PLATFORM" == "Linux" -a "$CHECK_CFI" == "1" ]; then
-  echo @@@BUILD_STEP run 64-bit cfi unit tests@@@
-  # FIXME: Make these true dependencies of check-cfi-and-supported when
-  # compiler-rt is configured as an external project.
-  (cd llvm_build64 && make -j$MAKE_JOBS LLVMgold opt sanstats && make -j$MAKE_JOBS check-cfi-and-supported) || echo @@@STEP_FAILURE@@@
+check_64bit 1 sanitizer
+check_64bit $CHECK_ASAN asan
+if [ "$PLATFORM" == "Linux" ]; then
+  check_64bit $CHECK_ASAN asan-dynamic
+  check_64bit $CHECK_CFI cfi-and-supported
+  check_64bit $CHECK_DFSAN dfsan
+  check_64bit $CHECK_LSAN lsan
+  check_64bit $CHECK_MSAN msan
+  check_64bit $CHECK_TSAN tsan
+  check_64bit $CHECK_UBSAN ubsan
 fi
 
 echo @@@BUILD_STEP run sanitizer_common tests@@@
@@ -261,40 +235,24 @@
       ${CMAKE_NINJA_OPTIONS} $LLVM_CHECKOUT)
   ln -sf llvm_build_ninja/compile_commands.json $LLVM_CHECKOUT
   (cd llvm_build_ninja && ninja) || echo @@@STEP_FAILURE@@@
-  echo @@@BUILD_STEP ninja check-sanitizer@@@
-  (cd llvm_build_ninja && ninja check-sanitizer) || echo @@@STEP_FAILURE@@@
-  if [ "$CHECK_ASAN" == 1 ]; then
-    echo @@@BUILD_STEP ninja check-asan@@@
-    (cd llvm_build_ninja && ninja check-asan) || echo @@@STEP_FAILURE@@@
-  fi
-  if [ "$CHECK_UBSAN" == 1 ]; then
-    echo @@@BUILD_STEP ninja check-ubsan@@@
-    (cd llvm_build_ninja && ninja check-ubsan) || echo @@@STEP_FAILURE@@@
-  fi
-  if [ "$CHECK_TSAN" == 1 ]; then
-    echo @@@BUILD_STEP ninja check-tsan@@@
-    (cd llvm_build_ninja && ninja check-tsan) || echo @@@STEP_FAILURE@@@
-  fi
-  if [ "$CHECK_SCUDO" == 1 ]; then
-    echo @@@BUILD_STEP ninja check-scudo@@@
-    (cd llvm_build_ninja && ninja check-scudo) || echo @@@STEP_FAILURE@@@
-  fi
-  if [ "$CHECK_MSAN" == 1 ]; then
-    echo @@@BUILD_STEP ninja check-msan@@@
-    (cd llvm_build_ninja && ninja check-msan) || echo @@@STEP_FAILURE@@@
-  fi
-  if [ "$CHECK_LSAN" == 1 ]; then
-    echo @@@BUILD_STEP ninja check-lsan@@@
-    (cd llvm_build_ninja && ninja check-lsan) || echo @@@STEP_FAILURE@@@
-  fi
-  if [ "$CHECK_DFSAN" == 1 ]; then
-    echo @@@BUILD_STEP ninja check-dfsan@@@
-    (cd llvm_build_ninja && ninja check-dfsan) || echo @@@STEP_WARNINGS@@@
-  fi
-  if [ "$CHECK_CFI" == 1 ]; then
-    echo @@@BUILD_STEP ninja check-cfi-and-supported@@@
-    (cd llvm_build_ninja && ninja check-cfi-and-supported) || echo @@@STEP_FAILURE@@@
-  fi
+
+  check_ninja() {
+    CONDITION=$1
+    SANITIZER=$2
+    if ["$CONDITION" == "1" ]; then
+      echo @@@BUILD_STEP ninja check-$SANITIZER@@@
+      (cd llvm_build_ninja && ninja check-$SANITIZER) || echo @@@STEP_FAILURE@@@
+    fi
+  }
+
+  check_ninja 1 sanitizer
+  check_ninja $CHECK_ASAN asan
+  check_ninja $CHECK_CFI cfi-and-supported
+  check_ninja $CHECK_DFSAN dfsan
+  check_ninja $CHECK_LSAN lsan
+  check_ninja $CHECK_MSAN msan
+  check_ninja $CHECK_TSAN tsan
+  check_ninja $CHECK_UBSAN ubsan
 fi
 
 if [ $BUILD_ANDROID == 1 ] ; then
Index: zorg/buildbot/builders/sanitizers/buildbot_functions.sh
===================================================================
--- zorg/buildbot/builders/sanitizers/buildbot_functions.sh
+++ zorg/buildbot/builders/sanitizers/buildbot_functions.sh
@@ -9,6 +9,7 @@
   else
     svn co "${repo}" "${tree}" $rev_arg
   fi
+  svn revert -R "${tree}"
 }
 
 function buildbot_update {
@@ -31,23 +32,24 @@
       fi
     done
 
-    update_or_checkout "$rev_arg" http://llvm.org/svn/llvm-project/llvm/trunk llvm
-
     if [ "$rev_arg" == "" ]; then
-        rev_arg="-r"$(svn info llvm | grep '^Revision:' | awk '{print $2}')
+        rev_arg="-r"$(svn info http://llvm.org/svn/llvm-project/llvm/trunk | grep '^Revision:' | awk '{print $2}')
     fi
 
+    update_or_checkout "$rev_arg" http://llvm.org/svn/llvm-project/llvm/trunk llvm &
+
     # XXX: Keep this list in sync with the change filter in buildbot/osuosl/master/master.cfg.
-    update_or_checkout "$rev_arg" http://llvm.org/svn/llvm-project/cfe/trunk llvm/tools/clang
-    update_or_checkout "$rev_arg" http://llvm.org/svn/llvm-project/compiler-rt/trunk llvm/projects/compiler-rt
+    update_or_checkout "$rev_arg" http://llvm.org/svn/llvm-project/cfe/trunk llvm/tools/clang &
+    update_or_checkout "$rev_arg" http://llvm.org/svn/llvm-project/compiler-rt/trunk llvm/projects/compiler-rt &
     if [ "$CHECK_LIBCXX" != "0" ]; then
-      update_or_checkout "$rev_arg" http://llvm.org/svn/llvm-project/libcxx/trunk llvm/projects/libcxx
-      update_or_checkout "$rev_arg" http://llvm.org/svn/llvm-project/libcxxabi/trunk llvm/projects/libcxxabi
-      update_or_checkout "$rev_arg" http://llvm.org/svn/llvm-project/libunwind/trunk llvm/projects/libunwind
+      update_or_checkout "$rev_arg" http://llvm.org/svn/llvm-project/libcxx/trunk llvm/projects/libcxx &
+      update_or_checkout "$rev_arg" http://llvm.org/svn/llvm-project/libcxxabi/trunk llvm/projects/libcxxabi &
+      update_or_checkout "$rev_arg" http://llvm.org/svn/llvm-project/libunwind/trunk llvm/projects/libunwind &
     fi
     if [ "$CHECK_LLD" != "0" ]; then
-      update_or_checkout "$rev_arg" http://llvm.org/svn/llvm-project/lld/trunk llvm/tools/lld
+      update_or_checkout "$rev_arg" http://llvm.org/svn/llvm-project/lld/trunk llvm/tools/lld &
     fi
+    wait
 }
 
 function set_chrome_suid_sandbox {