diff --git a/.travis.yml b/.travis.yml
index 3c52e78c..0399380d 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -48,8 +48,8 @@ matrix:
       compiler: gcc
       env: BUILD_TYPE=Release VERBOSE=1 CXX_FLAGS=-std=c++11 HOMEBREW_LOGS=~/homebrew-logs HOMEBREW_TEMP=~/homebrew-temp
     - os: osx
+      compiler: clang
       env: BUILD_TYPE=Release VERBOSE=1 CXX_FLAGS=-std=c++11 HOMEBREW_LOGS=~/homebrew-logs HOMEBREW_TEMP=~/homebrew-temp
-      if: type != pull_request
 
 # These are the install and build (script) phases for the most common entries in the matrix.  They could be included
 # in each entry in the matrix, but that is just repetitive.
@@ -73,6 +73,13 @@ addons:
     packages:
     - g++-4.9
     - clang-3.9
+    update: true
+  homebrew:
+    packages:
+    - ccache
+    - gcc@4.9
+    - llvm@3.9
+    update: true
 
 notifications:
   email: false
diff --git a/ci/env-osx.sh b/ci/env-osx.sh
index 03c2d15d..9c421e14 100755
--- a/ci/env-osx.sh
+++ b/ci/env-osx.sh
@@ -37,5 +37,11 @@
 #
 
 if [ "${TRAVIS_OS_NAME}" = "osx" ]; then
-    if [ "$CXX" = "clang++" ]; then export CXX="clang++-3.9" CC="clang-3.9"; fi
+    if [ "$CXX" = "clang++" ]; then
+        # $PATH needs to be adjusted because the llvm tap doesn't install the
+        # package to /usr/local/bin, etc, like the gcc tap does.
+        # See: https://github.com/Homebrew/legacy-homebrew/issues/29733
+        clang_version=3.9
+        export PATH="/usr/local/opt/llvm@${clang_version}/bin:$PATH";
+    fi
 fi
diff --git a/ci/install-osx.sh b/ci/install-osx.sh
index 6550ff51..f2baebd2 100755
--- a/ci/install-osx.sh
+++ b/ci/install-osx.sh
@@ -36,4 +36,5 @@ if [ "${TRAVIS_OS_NAME}" != "osx" ]; then
     exit 0
 fi
 
-brew install ccache
+brew update
+brew install ccache gcc@4.9 llvm@3.9