diff --git a/src/ci/docker/disabled/wasm32/Dockerfile b/src/ci/docker/disabled/wasm32/Dockerfile
index f3dd48ae411..025029c6745 100644
--- a/src/ci/docker/disabled/wasm32/Dockerfile
+++ b/src/ci/docker/disabled/wasm32/Dockerfile
@@ -11,7 +11,9 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   cmake \
   sudo \
   gdb \
-  xz-utils
+  xz-utils \
+  jq \
+  bzip2
 
 # dumb-init
 COPY scripts/dumb-init.sh /scripts/
@@ -22,6 +24,10 @@ COPY scripts/emscripten.sh /scripts/
 RUN bash /scripts/emscripten.sh
 COPY disabled/wasm32/node.sh /usr/local/bin/node
 
+# cache
+COPY scripts/sccache.sh /scripts/
+RUN sh /scripts/sccache.sh
+
 # env
 ENV PATH=$PATH:/emsdk-portable
 ENV PATH=$PATH:/emsdk-portable/clang/e1.37.13_64bit/
@@ -32,13 +38,9 @@ ENV EM_CONFIG=/emsdk-portable/.emscripten
 
 ENV TARGETS=wasm32-unknown-emscripten,wasm32-experimental-emscripten
 
-ENV RUST_CONFIGURE_ARGS --target=$TARGETS --experimental-targets=WebAssembly
+ENV RUST_CONFIGURE_ARGS --target=$TARGETS
 
 ENV SCRIPT python2.7 ../x.py test --target $TARGETS
 
-# cache
-COPY scripts/sccache.sh /scripts/
-RUN sh /scripts/sccache.sh
-
 # init
 ENTRYPOINT ["/usr/bin/dumb-init", "--"]
diff --git a/src/ci/docker/scripts/emscripten.sh b/src/ci/docker/scripts/emscripten.sh
index 516ef0ae0d2..e693f975f69 100644
--- a/src/ci/docker/scripts/emscripten.sh
+++ b/src/ci/docker/scripts/emscripten.sh
@@ -27,30 +27,38 @@ exit 1
   set -x
 }
 
+# Download emsdk
 cd /
 curl -L https://s3.amazonaws.com/mozilla-games/emscripten/releases/emsdk-portable.tar.gz | \
     tar -xz
 
+# Download last known good emscripten from WebAssembly waterfall
+BUILD=$(curl -L https://storage.googleapis.com/wasm-llvm/builds/linux/lkgr.json | \
+    jq '.build | tonumber')
+curl -L https://storage.googleapis.com/wasm-llvm/builds/linux/$BUILD/wasm-binaries.tbz2 | \
+    hide_output tar xvkj
+
+# node 8 is required to run wasm
+cd /
+curl -L https://nodejs.org/dist/v8.0.0/node-v8.0.0-linux-x64.tar.xz | \
+    tar -xJ
+
 cd /emsdk-portable
 ./emsdk update
 hide_output ./emsdk install sdk-1.37.13-64bit
 ./emsdk activate sdk-1.37.13-64bit
 
+# Make emscripten use wasm-ready node and LLVM tools
+echo "NODE_JS='/node-v8.0.0-linux-x64/bin/node'" >> /root/.emscripten
+echo "LLVM_ROOT='/wasm-install/bin'" >> /root/.emscripten
+
+# Make emsdk usable by any user
+cp /root/.emscripten /emsdk-portable
+chmod a+rxw -R /emsdk-portable
+
 # Compile and cache libc
 source ./emsdk_env.sh
 echo "main(){}" > a.c
 HOME=/emsdk-portable/ emcc a.c
 HOME=/emsdk-portable/ emcc -s WASM=1 a.c
 rm -f a.*
-
-# Make emscripten use Rust's LLVM
-echo "LLVM_ROOT='/checkout/obj/build/x86_64-unknown-linux-gnu/llvm/bin'" >> /root/.emscripten
-
-# Make emsdk usable by any user
-cp /root/.emscripten /emsdk-portable
-chmod a+rxw -R /emsdk-portable
-
-# node 8 is required to run wasm
-cd /
-curl -L https://nodejs.org/dist/v8.0.0/node-v8.0.0-linux-x64.tar.xz | \
-    tar -xJ