diff --git a/.travis.yml b/.travis.yml
index 59d61aa..59fd271 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -4,11 +4,7 @@
 
 language: cpp
 
-sudo: false
-
-dist: trusty
-
-python: "2.7"
+dist: xenial
 
 branches:
   only:
@@ -131,12 +127,12 @@ matrix:
             - ubuntu-toolchain-r-test
 
     - os: linux
-      compiler: g++-8
-      env: UBSAN=1 TOOLSET=gcc COMPILER=g++-8 CXXSTD=03,11,14,17,2a UBSAN_OPTIONS=print_stacktrace=1 LINKFLAGS=-fuse-ld=gold
+      compiler: g++-9
+      env: UBSAN=1 TOOLSET=gcc COMPILER=g++-9 CXXSTD=03,11,14,17,2a UBSAN_OPTIONS=print_stacktrace=1 LINKFLAGS=-fuse-ld=gold
       addons:
         apt:
           packages:
-            - g++-8
+            - g++-9
           sources:
             - ubuntu-toolchain-r-test
 
@@ -145,6 +141,7 @@ matrix:
       env: TOOLSET=clang COMPILER=clang++ CXXSTD=03,11
 
     - os: linux
+      dist: trusty
       compiler: /usr/bin/clang++
       env: TOOLSET=clang COMPILER=/usr/bin/clang++ CXXSTD=03,11
       addons:
@@ -153,6 +150,7 @@ matrix:
             - clang-3.3
 
     - os: linux
+      dist: trusty
       compiler: /usr/bin/clang++
       env: TOOLSET=clang COMPILER=/usr/bin/clang++ CXXSTD=03,11
       addons:
@@ -167,7 +165,6 @@ matrix:
         apt:
           packages:
             - clang-3.5
-            - libstdc++-4.9-dev
           sources:
             - ubuntu-toolchain-r-test
 
@@ -178,7 +175,16 @@ matrix:
         apt:
           packages:
             - clang-3.6
-            - libstdc++-4.9-dev
+          sources:
+            - ubuntu-toolchain-r-test
+
+    - os: linux
+      compiler: clang++-3.7
+      env: TOOLSET=clang COMPILER=clang++-3.7 CXXSTD=03,11,14,1z
+      addons:
+        apt:
+          packages:
+            - clang-3.7
           sources:
             - ubuntu-toolchain-r-test
 
@@ -189,7 +195,6 @@ matrix:
         apt:
           packages:
             - clang-3.8
-            - libstdc++-4.9-dev
           sources:
             - ubuntu-toolchain-r-test
 
@@ -200,7 +205,6 @@ matrix:
         apt:
           packages:
             - clang-3.9
-            - libstdc++-4.9-dev
           sources:
             - ubuntu-toolchain-r-test
 
@@ -211,10 +215,8 @@ matrix:
         apt:
           packages:
             - clang-4.0
-            - libstdc++-4.9-dev
           sources:
             - ubuntu-toolchain-r-test
-            - llvm-toolchain-trusty-4.0
 
     - os: linux
       compiler: clang++-5.0
@@ -223,10 +225,8 @@ matrix:
         apt:
           packages:
             - clang-5.0
-            - libstdc++-4.9-dev
           sources:
             - ubuntu-toolchain-r-test
-            - llvm-toolchain-trusty-5.0
 
     - os: linux
       compiler: clang++-6.0
@@ -237,7 +237,6 @@ matrix:
             - clang-6.0
           sources:
             - ubuntu-toolchain-r-test
-            - llvm-toolchain-trusty-6.0
 
     - os: linux
       compiler: clang++-7
@@ -248,7 +247,7 @@ matrix:
             - clang-7
           sources:
             - ubuntu-toolchain-r-test
-            - llvm-toolchain-trusty-7
+            - llvm-toolchain-xenial-7
 
     - os: linux
       compiler: clang++-8
@@ -259,10 +258,9 @@ matrix:
             - clang-8
           sources:
             - ubuntu-toolchain-r-test
-            - llvm-toolchain-trusty-8
+            - llvm-toolchain-xenial-8
 
     - os: linux
-      dist: xenial
       compiler: clang++-9
       env: TOOLSET=clang COMPILER=clang++-9 CXXSTD=03,11,14,17,2a
       addons:
@@ -275,17 +273,18 @@ matrix:
               key_url: 'https://apt.llvm.org/llvm-snapshot.gpg.key'
 
     - os: linux
-      compiler: clang++-6.0
-      env: UBSAN=1 TOOLSET=clang COMPILER=clang++-6.0 CXXSTD=03,11,14,17 UBSAN_OPTIONS=print_stacktrace=1
+      compiler: clang++-8
+      env: UBSAN=1 TOOLSET=clang COMPILER=clang++-8 CXXSTD=03,11,14,17,2a UBSAN_OPTIONS=print_stacktrace=1
       addons:
         apt:
           packages:
-            - clang-6.0
+            - clang-8
           sources:
             - ubuntu-toolchain-r-test
-            - llvm-toolchain-trusty-6.0
+            - llvm-toolchain-xenial-8
 
     - os: linux
+      dist: trusty
       compiler: clang++-libc++
       env: TOOLSET=clang COMPILER=clang++-libc++ CXXSTD=03,11,14,1z
       addons:
@@ -294,6 +293,7 @@ matrix:
             - libc++-dev
 
     - os: linux
+      dist: trusty
       compiler: clang++-libc++
       env: UBSAN=1 TOOLSET=clang COMPILER=clang++-libc++ CXXSTD=03,11,14,1z UBSAN_OPTIONS=print_stacktrace=1
       addons:
@@ -305,6 +305,10 @@ matrix:
       compiler: clang++
       env: TOOLSET=clang COMPILER=clang++ CXXSTD=03,11,14,1z
 
+    - os: osx
+      compiler: clang++
+      env: UBSAN=1 TOOLSET=clang COMPILER=clang++ CXXSTD=03,11,14,1z UBSAN_OPTIONS=print_stacktrace=1
+
     - os: linux
       env: CMAKE=1
       script: