diff --git a/.circleci/config.yml b/.circleci/config.yml
index e30b5b45b..d804afce9 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -37,6 +37,21 @@ jobs:
       - run: make
       - run: make check || .ci/fail.sh
 
+  clang-O3-O0:
+    docker:
+      - image: multiarch/crossbuild
+    steps:
+      - checkout
+      - run: apt update && apt install -y ragel libfreetype6-dev libglib2.0-dev libcairo2-dev libicu-dev libgraphite2-dev python python-pip
+      - run: pip install fonttools
+      - run: wget http://download.savannah.gnu.org/releases/freetype/freetype-2.9.tar.bz2 && tar xf freetype-2.9.tar.bz2 && cd freetype-2.9 && ./autogen.sh && ./configure && make -j4 && cd ..
+      - run: CFLAGS="-O3" CXXFLAGS="-O3" CC=clang CXX=clang++ ./autogen.sh --with-freetype --with-glib --with-cairo --with-icu --with-graphite2
+      - run: make
+      - run: LD_LIBRARY_PATH="$PWD/freetype-2.9/objs/.libs" make check || .ci/fail.sh
+      - run: CFLAGS="-O0" CXXFLAGS="-O0" CC=clang CXX=clang++ ./autogen.sh --with-freetype --with-glib --with-cairo --with-icu --with-graphite2
+      - run: make
+      - run: LD_LIBRARY_PATH="$PWD/freetype-2.9/objs/.libs" make check || .ci/fail.sh
+
   fedora-outoftreebuild:
     docker:
       - image: fedora
@@ -153,6 +168,7 @@ workflows:
       # autotools based builds
       - alpine-O3
       - archlinux-debug-O0
+      - clang-O3-O0
       - fedora-outoftreebuild
 
       # cmake based builds