diff --git a/.travis.yml b/.travis.yml
index 3248314..2415029 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -6,7 +6,7 @@ language: cpp
 
 sudo: false
 
-dist: trusty
+dist: xenial
 
 branches:
   only:
@@ -133,6 +133,7 @@ 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:
@@ -141,6 +142,7 @@ matrix:
             - clang-3.3
 
     - os: linux
+      dist: trusty
       compiler: /usr/bin/clang++
       env: TOOLSET=clang COMPILER=/usr/bin/clang++ CXXSTD=03,11
       addons:
@@ -155,10 +157,8 @@ matrix:
         apt:
           packages:
             - clang-3.5
-            - libstdc++-4.9-dev
           sources:
             - ubuntu-toolchain-r-test
-            - llvm-toolchain-precise-3.5
 
     - os: linux
       compiler: clang++-3.6
@@ -169,7 +169,6 @@ matrix:
             - clang-3.6
           sources:
             - ubuntu-toolchain-r-test
-            - llvm-toolchain-precise-3.6
 
     - os: linux
       compiler: clang++-3.7
@@ -180,7 +179,6 @@ matrix:
             - clang-3.7
           sources:
             - ubuntu-toolchain-r-test
-            - llvm-toolchain-precise-3.7
 
     - os: linux
       compiler: clang++-3.8
@@ -189,10 +187,8 @@ matrix:
         apt:
           packages:
             - clang-3.8
-            - libstdc++-4.9-dev
           sources:
             - ubuntu-toolchain-r-test
-            - llvm-toolchain-precise-3.8
 
     - os: linux
       compiler: clang++-3.9
@@ -201,10 +197,8 @@ matrix:
         apt:
           packages:
             - clang-3.9
-            - libstdc++-4.9-dev
           sources:
             - ubuntu-toolchain-r-test
-            - llvm-toolchain-precise-3.9
 
     - os: linux
       compiler: clang++-4.0
@@ -215,7 +209,6 @@ matrix:
             - clang-4.0
           sources:
             - ubuntu-toolchain-r-test
-            - llvm-toolchain-trusty-4.0
 
     - os: linux
       compiler: clang++-5.0
@@ -226,7 +219,6 @@ matrix:
             - clang-5.0
           sources:
             - ubuntu-toolchain-r-test
-            - llvm-toolchain-trusty-5.0
 
     - os: linux
       compiler: clang++-6.0
@@ -237,7 +229,6 @@ matrix:
             - clang-6.0
           sources:
             - ubuntu-toolchain-r-test
-            - llvm-toolchain-trusty-6.0
 
     - os: linux
       compiler: clang++-7
@@ -248,7 +239,7 @@ matrix:
             - clang-7
           sources:
             - ubuntu-toolchain-r-test
-            - llvm-toolchain-trusty-7
+            - llvm-toolchain-xenial-7
 
     - os: linux
       compiler: clang++-8
@@ -259,11 +250,24 @@ matrix:
             - clang-8
           sources:
             - ubuntu-toolchain-r-test
-            - llvm-toolchain-trusty-8
+            - llvm-toolchain-xenial-8
 
     - os: linux
+      compiler: clang++-9
+      env: TOOLSET=clang COMPILER=clang++-9 CXXSTD=03,11,14,17,2a
+      addons:
+        apt:
+          packages:
+            - clang-9
+          sources:
+            - ubuntu-toolchain-r-test
+            - sourceline: 'deb https://apt.llvm.org/xenial/ llvm-toolchain-xenial-9 main'
+              key_url: 'https://apt.llvm.org/llvm-snapshot.gpg.key'
+
+    - os: linux
+      dist: trusty
       compiler: clang++-libc++
-      env: TOOLSET=clang COMPILER=clang++-libc++ CXXSTD=03,11,14,1z VARIANT=release
+      env: TOOLSET=clang COMPILER=clang++-libc++ CXXSTD=03,11,14,1z
       addons:
         apt:
           packages: