diff --git a/.gitmodules b/.gitmodules
index 35a56e3..898620e 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,6 +1,6 @@
 [submodule "multibuild"]
 	path = multibuild
-	url = https://github.com/riddell-stan/multibuild
+	url = https://github.com/matthew-brett/multibuild.git
 [submodule "pystan"]
 	path = pystan
 	url = https://github.com/stan-dev/pystan
diff --git a/.travis.yml b/.travis.yml
index 82d1a89..7950ec2 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,109 +1,91 @@
+version: ~> 1.0
 env:
-    global:
-        - REPO_DIR=pystan
-        - BUILD_COMMIT=v2.19.1.1
-        - BUILD_DEPENDS=Cython
-        - TEST_DEPENDS=
-        - PLAT=x86_64
-        - UNICODE_WIDTH=32
-        - NP_BUILD_DEP=1.8.2
-        - WHEELHOUSE_UPLOADER_USERNAME=pystan-worker
-        - WHEELHOUSE_UPLOADER_REGION=IAD
-        # custom manylinux image with newer gcc
-        - DOCKER_IMAGE=tktechdocker/manylinux:gcc8.3.0
-        # Following generated with
-        # travis encrypt -r stan-dev/pystan-wheels WHEELHOUSE_UPLOADER_SECRET=<the api key>
-        - secure: "RPK/AsxmDNiiJ5WZwRr8oN5Ybj+/IaCNp/zF8ZwOO4XXG0RF56n1fGeqW+tfHhsOjjwBZtYmQSqSDrcd3cQw564yoBpbTy1YIFPMVP5gELFE4xw9A7KGOcGJ22RMNbqAq4esl8YqOLVjLsFQbx0aCrcRripnj0tjK/6nOemYt6+Oo8rm2SZjRnclmE7UsVSoYYll/cE+H/wTLZo3nHnRl6JZUcTa5dQ6i/GUR+kMzA7u4yGI6n16THeBIVI6dAOgabmInahZad6v7EwUWGZrwUHBmQmZhqMkPU9YVEd3I4MUgJ/9acl4ezlQuEZ4CfagSKqWMUpa1nqjsuNf374wZRi3jv4urTd6ouk+32TkFBQDHrBpdSCRgzn1Vp9Pogs4sThIgUOSEDx90nS9lhmQ5EFm8fIz2W4h1Relo0ra+FKvahIBpMCSW20Ozty4GiyY4bIYt9vzSZCblp5HlxWF5UW1zRIExtJvSipSEHElk8SvFryunFacqt2T36OeaYhp2mA5LGqTcNWMTTNsM4Z0Vw7CzeB9KOgTT1FRKVjM9oiVO9blAj0TkseBYnR0PuQ6EdHmNq8bO+oupaafca/cq6j7GRiv5n7pL66LV75xv+8gQ4VpLY6Z31+DRZ74eh/nobsIJobYz6H5N8wjhuGZAtMHIeisZrdjWLOGiqGa9KY="
-
+  global:
+    - REPO_DIR=pystan
+    - BUILD_COMMIT=v2.19.1.1
+    - BUILD_DEPENDS=Cython
+    - TEST_DEPENDS=
+    - MB_ML_VER=2014
+    - DOCKER_TEST_IMAGE=multibuild/xenial_x86_64
+    - PLAT=x86_64
+    - UNICODE_WIDTH=32
+    - NP_BUILD_DEP=1.8.2
+    - WHEELHOUSE_UPLOADER_USERNAME=pystan-worker
+    - WHEELHOUSE_UPLOADER_REGION=IAD
+    - DOCKER_IMAGE=quay.io/pypa/manylinux1_x86_64
+    # Following generated with
+    # travis encrypt -r stan-dev/pystan-wheels WHEELHOUSE_UPLOADER_SECRET=<the api key>
+    - secure: "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"
 
 language: python
 cache:
   - pip
 python: 3.5
-dist: trusty
+dist: xenial
 services: docker
 
-matrix:
-  exclude:
-      # Exclude the default Python 3.5 build
-      - python: 3.5
-  include:
-    - os: linux
-      env:
-        - MB_PYTHON_VERSION=2.7
-    - os: linux
-      env:
-        - MB_PYTHON_VERSION=2.7
-        - UNICODE_WIDTH=16
-    - os: linux
-      env:
-        - MB_PYTHON_VERSION=3.5
-        - NP_BUILD_DEP="1.9.3"
-    - os: linux
-      env:
-        - MB_PYTHON_VERSION=3.6
-        - NP_BUILD_DEP="1.9.3"
-    - os: linux
-      env:
-        - MB_PYTHON_VERSION=3.7
-        - NP_BUILD_DEP=1.14.5
-    - os: linux
-      env:
-        - MB_PYTHON_VERSION=3.8
-        - NP_BUILD_DEP=1.14.5
-    - os: osx
-      language: objective-c
-      env:
-        - MB_PYTHON_VERSION=2.7
-    - os: osx
-      language: objective-c
-      env:
-        - MB_PYTHON_VERSION=3.5
-        - NP_BUILD_DEP="1.9.3"
-    - os: osx
-      language: objective-c
-      env:
-        - MB_PYTHON_VERSION=3.6
-        - NP_BUILD_DEP="1.9.3"
-    - os: osx
-      language: generic
-      env:
-        - MB_PYTHON_VERSION=3.7
-        - NP_BUILD_DEP=1.14.5
-    - os: osx
-      language: generic
-      env:
-        - MB_PYTHON_VERSION=3.8
-        - NP_BUILD_DEP=1.14.5
+jobs:
+  - os: linux
+    env:
+      - MB_PYTHON_VERSION=3.6
+      - NP_BUILD_DEP="1.9.3"
+  - os: linux
+    env:
+      - MB_PYTHON_VERSION=3.7
+      - NP_BUILD_DEP=1.14.5
+  - os: linux
+    env:
+      - MB_PYTHON_VERSION=3.8
+      - NP_BUILD_DEP=1.14.5
+  - os: osx
+    language: objective-c
+    env:
+      - MB_PYTHON_VERSION=3.6
+      - NP_BUILD_DEP="1.9.3"
+  - os: osx
+    language: generic
+    env:
+      - MB_PYTHON_VERSION=3.7
+      - NP_BUILD_DEP=1.14.5
+  - os: osx
+    language: generic
+    env:
+      - MB_PYTHON_VERSION=3.8
+      - NP_BUILD_DEP=1.14.5
 before_install:
-    - BUILD_DEPENDS="numpy==$NP_BUILD_DEP ${BUILD_DEPENDS}"
-    - source multibuild/common_utils.sh
-    - source multibuild/travis_steps.sh
-    - before_install
+  - BUILD_DEPENDS="numpy==$NP_BUILD_DEP ${BUILD_DEPENDS}"
+  - source multibuild/common_utils.sh
+  - source multibuild/travis_steps.sh
+  - before_install
 
 install:
-    # Maybe get and clean and patch source
-    - clean_code $REPO_DIR $BUILD_COMMIT
-    # remove unused files from pystan/pystan/stan to save space and avoid problems on manylinux1
-    # these cleaning steps may be removed after manylinux1 is retired. See this issue for more:
-    # https://github.com/pypa/auditwheel/issues/145
-    # cleanup steps start
-    - find pystan/pystan/stan/lib -type d -iname doc -print0 | xargs -0 rm -rf
-    - find pystan/pystan/stan/lib/stan_math/lib -type d -name test -print0 | xargs -0 rm -rf
-    - find pystan/pystan/stan/lib/stan_math/lib -maxdepth 2 -type d -name libs -print0 | xargs -0 rm -rf
-    - find pystan/pystan/stan/lib/stan_math/lib -maxdepth 2 -type d -name tools -print0 | xargs -0 rm -rf
-    # cleanup steps end
-    # osx wheels take a particularly long time to build
-    - travis_wait 40 build_wheel $REPO_DIR $PLAT
+  # Maybe get and clean and patch source
+  - clean_code $REPO_DIR $BUILD_COMMIT
+  # remove unused files from pystan/pystan/stan to save space and avoid problems on manylinux1
+  # these cleaning steps may be removed after manylinux1 is retired. See this issue for more:
+  # https://github.com/pypa/auditwheel/issues/145
+  # cleanup steps start
+  - find pystan/pystan/stan/lib -type d -iname doc -print0 | xargs -0 rm -rf
+  - find pystan/pystan/stan/lib/stan_math/lib -type d -name test -print0 | xargs -0 rm -rf
+  - find pystan/pystan/stan/lib/stan_math/lib -maxdepth 2 -type d -name libs -print0 | xargs -0 rm -rf
+  - find pystan/pystan/stan/lib/stan_math/lib -maxdepth 2 -type d -name tools -print0 | xargs -0 rm -rf
+  # cleanup steps end
+  # osx wheels take a particularly long time to build
+  - |
+    if [ ${TRAVIS_OS_NAME} = "osx" ]; then
+      travis_wait 60 build_wheel $REPO_DIR
+    else
+      build_wheel $REPO_DIR
+    fi
 
 script:
-    - install_run $PLAT
+  - install_run $PLAT
 
 after_success:
-    # Upload wheels to Rackspace container
-    - pip install wheelhouse-uploader
-    - travis_wait 40 python -m wheelhouse_uploader upload --local-folder
-          ${TRAVIS_BUILD_DIR}/wheelhouse/
-          --no-update-index
-          --region=${WHEELHOUSE_UPLOADER_REGION}
-          wheels
+  # Upload wheels to Rackspace container
+  - pip install wheelhouse-uploader
+  - travis_wait 40 python -m wheelhouse_uploader upload --local-folder
+        ${TRAVIS_BUILD_DIR}/wheelhouse/
+        --no-update-index
+        --region=${WHEELHOUSE_UPLOADER_REGION}
+        wheels
diff --git a/env_vars.sh b/env_vars.sh
index c2212fd..120c1b7 100644
--- a/env_vars.sh
+++ b/env_vars.sh
@@ -1,5 +1,3 @@
 # See multibuild/README.rst
 export MACOSX_DEPLOYMENT_TARGET=10.9
 export CFLAGS="-static-libstdc++"
-export CC=/usr/local/gcc-8.3.0/bin/gcc-8.3.0
-export CXX=/usr/local/gcc-8.3.0/bin/g++-8.3.0
diff --git a/multibuild b/multibuild
index c40a01c..da36cd5 160000
--- a/multibuild
+++ b/multibuild
@@ -1 +1 @@
-Subproject commit c40a01c595b8bb09b3be8829b857437523009042
+Subproject commit da36cd5408e03cad504217de4a21bb8f19f2fb2f