diff --git a/ci/docker/aarch64-unknown-linux-gnu/Dockerfile b/ci/docker/aarch64-unknown-linux-gnu/Dockerfile
index 9e2559f4..02e9f5ad 100644
--- a/ci/docker/aarch64-unknown-linux-gnu/Dockerfile
+++ b/ci/docker/aarch64-unknown-linux-gnu/Dockerfile
@@ -1,8 +1,10 @@
 FROM ubuntu:18.04
-RUN apt-get update && \
+RUN dpkg --add-architecture arm64 && \
+    apt-get update && \
     apt-get install -y --no-install-recommends \
     gcc libc6-dev ca-certificates \
     gcc-aarch64-linux-gnu libc6-dev-arm64-cross \
+    clang libclang-common-6.0-dev:arm64 \
     qemu-user-static
 ENV CARGO_TARGET_AARCH64_UNKNOWN_LINUX_GNU_LINKER=aarch64-linux-gnu-gcc \
     CARGO_TARGET_AARCH64_UNKNOWN_LINUX_GNU_RUNNER=qemu-aarch64-static \
diff --git a/ci/docker/arm-unknown-linux-gnueabi/Dockerfile b/ci/docker/arm-unknown-linux-gnueabi/Dockerfile
index afab874b..a8e8dfee 100644
--- a/ci/docker/arm-unknown-linux-gnueabi/Dockerfile
+++ b/ci/docker/arm-unknown-linux-gnueabi/Dockerfile
@@ -1,7 +1,7 @@
 FROM ubuntu:18.04
 RUN apt-get update && \
     apt-get install -y --no-install-recommends \
-    gcc libc6-dev ca-certificates \
+    gcc clang libc6-dev ca-certificates \
     gcc-arm-linux-gnueabi libc6-dev-armel-cross qemu-user-static
 ENV CARGO_TARGET_ARM_UNKNOWN_LINUX_GNUEABI_LINKER=arm-linux-gnueabi-gcc \
     CARGO_TARGET_ARM_UNKNOWN_LINUX_GNUEABI_RUNNER=qemu-arm-static \
diff --git a/ci/docker/arm-unknown-linux-gnueabihf/Dockerfile b/ci/docker/arm-unknown-linux-gnueabihf/Dockerfile
index 3ed3602b..e7560ae7 100644
--- a/ci/docker/arm-unknown-linux-gnueabihf/Dockerfile
+++ b/ci/docker/arm-unknown-linux-gnueabihf/Dockerfile
@@ -1,7 +1,7 @@
 FROM ubuntu:18.04
 RUN apt-get update && \
     apt-get install -y --no-install-recommends \
-    gcc libc6-dev ca-certificates \
+    gcc clang libc6-dev ca-certificates \
     gcc-arm-linux-gnueabihf libc6-dev-armhf-cross qemu-user-static
 ENV CARGO_TARGET_ARM_UNKNOWN_LINUX_GNUEABIHF_LINKER=arm-linux-gnueabihf-gcc \
     CARGO_TARGET_ARM_UNKNOWN_LINUX_GNUEABIHF_RUNNER=qemu-arm-static \
diff --git a/ci/docker/armv7-unknown-linux-gnueabihf/Dockerfile b/ci/docker/armv7-unknown-linux-gnueabihf/Dockerfile
index 6617af15..2f968b1c 100644
--- a/ci/docker/armv7-unknown-linux-gnueabihf/Dockerfile
+++ b/ci/docker/armv7-unknown-linux-gnueabihf/Dockerfile
@@ -1,7 +1,7 @@
 FROM ubuntu:18.04
 RUN apt-get update && \
     apt-get install -y --no-install-recommends \
-    gcc libc6-dev ca-certificates \
+    gcc clang libc6-dev ca-certificates \
     gcc-arm-linux-gnueabihf libc6-dev-armhf-cross qemu-user-static
 ENV CARGO_TARGET_ARMV7_UNKNOWN_LINUX_GNUEABIHF_LINKER=arm-linux-gnueabihf-gcc \
     CARGO_TARGET_ARMV7_UNKNOWN_LINUX_GNUEABIHF_RUNNER=qemu-arm-static \
diff --git a/ci/docker/i586-unknown-linux-gnu/Dockerfile b/ci/docker/i586-unknown-linux-gnu/Dockerfile
index 5783e28e..655479ba 100644
--- a/ci/docker/i586-unknown-linux-gnu/Dockerfile
+++ b/ci/docker/i586-unknown-linux-gnu/Dockerfile
@@ -1,4 +1,4 @@
 FROM ubuntu:18.04
 RUN apt-get update && \
     apt-get install -y --no-install-recommends \
-    gcc-multilib libc6-dev ca-certificates
+    gcc-multilib clang libc6-dev ca-certificates
diff --git a/ci/docker/i686-unknown-linux-gnu/Dockerfile b/ci/docker/i686-unknown-linux-gnu/Dockerfile
index 5783e28e..655479ba 100644
--- a/ci/docker/i686-unknown-linux-gnu/Dockerfile
+++ b/ci/docker/i686-unknown-linux-gnu/Dockerfile
@@ -1,4 +1,4 @@
 FROM ubuntu:18.04
 RUN apt-get update && \
     apt-get install -y --no-install-recommends \
-    gcc-multilib libc6-dev ca-certificates
+    gcc-multilib clang libc6-dev ca-certificates
diff --git a/ci/docker/mips-unknown-linux-gnu/Dockerfile b/ci/docker/mips-unknown-linux-gnu/Dockerfile
index f47e8f52..ab7126e6 100644
--- a/ci/docker/mips-unknown-linux-gnu/Dockerfile
+++ b/ci/docker/mips-unknown-linux-gnu/Dockerfile
@@ -2,7 +2,7 @@ FROM ubuntu:18.04
 
 RUN apt-get update && \
     apt-get install -y --no-install-recommends \
-    gcc libc6-dev ca-certificates \
+    gcc clang libc6-dev ca-certificates \
     gcc-mips-linux-gnu libc6-dev-mips-cross \
     binfmt-support qemu-user-static qemu-system-mips
 
diff --git a/ci/docker/mips64-unknown-linux-gnuabi64/Dockerfile b/ci/docker/mips64-unknown-linux-gnuabi64/Dockerfile
index 8fa77c7b..0f5ae676 100644
--- a/ci/docker/mips64-unknown-linux-gnuabi64/Dockerfile
+++ b/ci/docker/mips64-unknown-linux-gnuabi64/Dockerfile
@@ -4,6 +4,7 @@ RUN apt-get update && \
     ca-certificates \
     gcc \
     gcc-mips64-linux-gnuabi64 \
+    clang \
     libc6-dev \
     libc6-dev-mips64-cross \
     qemu-user-static \
diff --git a/ci/docker/mips64el-unknown-linux-gnuabi64/Dockerfile b/ci/docker/mips64el-unknown-linux-gnuabi64/Dockerfile
index c6611d9a..ab1b11c6 100644
--- a/ci/docker/mips64el-unknown-linux-gnuabi64/Dockerfile
+++ b/ci/docker/mips64el-unknown-linux-gnuabi64/Dockerfile
@@ -4,6 +4,7 @@ RUN apt-get update && \
     ca-certificates \
     gcc \
     gcc-mips64el-linux-gnuabi64 \
+    clang \
     libc6-dev \
     libc6-dev-mips64el-cross \
     qemu-user-static
diff --git a/ci/docker/mipsel-unknown-linux-gnu/Dockerfile b/ci/docker/mipsel-unknown-linux-gnu/Dockerfile
index 0bc69562..5012e014 100644
--- a/ci/docker/mipsel-unknown-linux-gnu/Dockerfile
+++ b/ci/docker/mipsel-unknown-linux-gnu/Dockerfile
@@ -2,7 +2,7 @@ FROM ubuntu:18.04
 
 RUN apt-get update && \
     apt-get install -y --no-install-recommends \
-    gcc libc6-dev ca-certificates \
+    gcc clang libc6-dev ca-certificates \
     gcc-mipsel-linux-gnu libc6-dev-mipsel-cross \
     binfmt-support qemu-user-static
 
diff --git a/ci/docker/powerpc-unknown-linux-gnu/Dockerfile b/ci/docker/powerpc-unknown-linux-gnu/Dockerfile
index 2d39fef6..87c49983 100644
--- a/ci/docker/powerpc-unknown-linux-gnu/Dockerfile
+++ b/ci/docker/powerpc-unknown-linux-gnu/Dockerfile
@@ -2,7 +2,7 @@ FROM ubuntu:18.04
 
 RUN apt-get update && \
     apt-get install -y --no-install-recommends \
-    gcc libc6-dev qemu-user-static ca-certificates \
+    gcc clang libc6-dev qemu-user-static ca-certificates \
     gcc-powerpc-linux-gnu libc6-dev-powerpc-cross \
     qemu-system-ppc
 
diff --git a/ci/docker/powerpc64-unknown-linux-gnu/Dockerfile b/ci/docker/powerpc64-unknown-linux-gnu/Dockerfile
index 653cd351..2fb77d50 100644
--- a/ci/docker/powerpc64-unknown-linux-gnu/Dockerfile
+++ b/ci/docker/powerpc64-unknown-linux-gnu/Dockerfile
@@ -2,7 +2,7 @@ FROM ubuntu:18.04
 
 RUN apt-get update && \
     apt-get install -y --no-install-recommends \
-    gcc libc6-dev ca-certificates \
+    gcc clang libc6-dev ca-certificates \
     gcc-powerpc64-linux-gnu libc6-dev-ppc64-cross \
     binfmt-support qemu-user-static qemu-system-ppc
 
diff --git a/ci/docker/powerpc64le-unknown-linux-gnu/Dockerfile b/ci/docker/powerpc64le-unknown-linux-gnu/Dockerfile
index 63ea9af9..fa011ce6 100644
--- a/ci/docker/powerpc64le-unknown-linux-gnu/Dockerfile
+++ b/ci/docker/powerpc64le-unknown-linux-gnu/Dockerfile
@@ -2,7 +2,7 @@ FROM ubuntu:18.04
 
 RUN apt-get update && \
     apt-get install -y --no-install-recommends \
-    gcc libc6-dev qemu-user-static ca-certificates \
+    gcc clang libc6-dev qemu-user-static ca-certificates \
     gcc-powerpc64le-linux-gnu libc6-dev-ppc64el-cross \
     qemu-system-ppc
 
diff --git a/ci/docker/thumbv6m-none-eabi/Dockerfile b/ci/docker/thumbv6m-none-eabi/Dockerfile
index 04d4f442..a080c959 100644
--- a/ci/docker/thumbv6m-none-eabi/Dockerfile
+++ b/ci/docker/thumbv6m-none-eabi/Dockerfile
@@ -1,7 +1,7 @@
 FROM ubuntu:18.04
 RUN apt-get update && \
     apt-get install -y --no-install-recommends \
-    gcc libc6-dev ca-certificates \
+    gcc clang libc6-dev ca-certificates \
     gcc-arm-none-eabi \
     libnewlib-arm-none-eabi
 ENV XARGO=1
diff --git a/ci/docker/thumbv7em-none-eabi/Dockerfile b/ci/docker/thumbv7em-none-eabi/Dockerfile
index 04d4f442..a080c959 100644
--- a/ci/docker/thumbv7em-none-eabi/Dockerfile
+++ b/ci/docker/thumbv7em-none-eabi/Dockerfile
@@ -1,7 +1,7 @@
 FROM ubuntu:18.04
 RUN apt-get update && \
     apt-get install -y --no-install-recommends \
-    gcc libc6-dev ca-certificates \
+    gcc clang libc6-dev ca-certificates \
     gcc-arm-none-eabi \
     libnewlib-arm-none-eabi
 ENV XARGO=1
diff --git a/ci/docker/thumbv7em-none-eabihf/Dockerfile b/ci/docker/thumbv7em-none-eabihf/Dockerfile
index 04d4f442..a080c959 100644
--- a/ci/docker/thumbv7em-none-eabihf/Dockerfile
+++ b/ci/docker/thumbv7em-none-eabihf/Dockerfile
@@ -1,7 +1,7 @@
 FROM ubuntu:18.04
 RUN apt-get update && \
     apt-get install -y --no-install-recommends \
-    gcc libc6-dev ca-certificates \
+    gcc clang libc6-dev ca-certificates \
     gcc-arm-none-eabi \
     libnewlib-arm-none-eabi
 ENV XARGO=1
diff --git a/ci/docker/thumbv7m-none-eabi/Dockerfile b/ci/docker/thumbv7m-none-eabi/Dockerfile
index 04d4f442..a080c959 100644
--- a/ci/docker/thumbv7m-none-eabi/Dockerfile
+++ b/ci/docker/thumbv7m-none-eabi/Dockerfile
@@ -1,7 +1,7 @@
 FROM ubuntu:18.04
 RUN apt-get update && \
     apt-get install -y --no-install-recommends \
-    gcc libc6-dev ca-certificates \
+    gcc clang libc6-dev ca-certificates \
     gcc-arm-none-eabi \
     libnewlib-arm-none-eabi
 ENV XARGO=1
diff --git a/ci/docker/x86_64-unknown-linux-gnu/Dockerfile b/ci/docker/x86_64-unknown-linux-gnu/Dockerfile
index 98000f4e..09cb0a44 100644
--- a/ci/docker/x86_64-unknown-linux-gnu/Dockerfile
+++ b/ci/docker/x86_64-unknown-linux-gnu/Dockerfile
@@ -1,4 +1,4 @@
 FROM ubuntu:18.04
 RUN apt-get update && \
     apt-get install -y --no-install-recommends \
-    gcc libc6-dev ca-certificates
+    gcc clang libc6-dev ca-certificates
diff --git a/ci/run-docker.sh b/ci/run-docker.sh
index 4bb2a78d..93ba5d3b 100755
--- a/ci/run-docker.sh
+++ b/ci/run-docker.sh
@@ -18,6 +18,7 @@ run() {
            --user $(id -u):$(id -g) \
            -e CARGO_HOME=/cargo \
            -e CARGO_TARGET_DIR=/target \
+           -e CLANG=clang \
            -e RUST_COMPILER_RT_ROOT \
            -v $(dirname $(dirname `which cargo`)):/cargo \
            -v `pwd`/target:/target \
diff --git a/ci/run.sh b/ci/run.sh
index ae32806e..254f8da6 100755
--- a/ci/run.sh
+++ b/ci/run.sh
@@ -18,6 +18,10 @@ cargo build --target $1
 cargo build --target $1 --release
 cargo build --target $1 --features c
 cargo build --target $1 --release --features c
+if [ -n "$CLANG" -o -n "$LLVM_CONFIG" ]; then
+cargo build --target $1 --features c-system
+cargo build --target $1 --release --features c-system
+fi
 
 PREFIX=$(echo $1 | sed -e 's/unknown-//')-
 case $1 in
@@ -77,6 +81,10 @@ RUSTFLAGS="-C debug-assertions=no" $build_intrinsics
 RUSTFLAGS="-C debug-assertions=no" $build_intrinsics --release
 RUSTFLAGS="-C debug-assertions=no" $build_intrinsics --features c
 RUSTFLAGS="-C debug-assertions=no" $build_intrinsics --features c --release
+if [ -n "$CLANG" -o -n "$LLVM_CONFIG" ]; then
+RUSTFLAGS="-C debug-assertions=no" $build_intrinsics --features c-system
+RUSTFLAGS="-C debug-assertions=no" $build_intrinsics --features c-system --release
+fi
 
 # Verify that there are no undefined symbols to `panic` within our
 # implementations