diff --git a/.travis.yml b/.travis.yml
index 5e1906a5c7..c6c42a08ba 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -3,6 +3,8 @@ cache:
   directories:
     - $HOME/.gem/ruby
     - Library/Homebrew/vendor/bundle
+    # For parallel_rspec
+    - Library/Homebrew/tmp
 
 matrix:
   include:
@@ -10,6 +12,7 @@ matrix:
       osx_image: xcode8.3
       rvm: system
     - os: linux
+      sudo: false
       rvm: 2.0.0
 
 before_install:
diff --git a/Library/Homebrew/dev-cmd/tap-new.rb b/Library/Homebrew/dev-cmd/tap-new.rb
index 48449e98d5..dcb41265cb 100644
--- a/Library/Homebrew/dev-cmd/tap-new.rb
+++ b/Library/Homebrew/dev-cmd/tap-new.rb
@@ -49,6 +49,10 @@ module Homebrew
       env: OSX=10.12
       osx_image: xcode8.3
       rvm: system
+      cache:
+        directories:
+          - $HOME/.gem/ruby
+          - Library/Homebrew/vendor/bundle
 
       before_install:
         - export TRAVIS_COMMIT="$(git rev-parse --verify -q HEAD)"
diff --git a/Library/Homebrew/dev-cmd/tests.rb b/Library/Homebrew/dev-cmd/tests.rb
index 72d6143fcf..d903267684 100644
--- a/Library/Homebrew/dev-cmd/tests.rb
+++ b/Library/Homebrew/dev-cmd/tests.rb
@@ -79,20 +79,24 @@ module Homebrew
         Dir.glob("test/**/*_spec.rb").reject { |p| p =~ %r{^test/vendor/bundle/} }
       end
 
-      opts = []
-
-      if ENV["CI"]
-        opts << "--combine-stderr"
-        opts << "--serialize-stdout"
+      opts = if ENV["CI"]
+        %w[
+          --combine-stderr
+          --serialize-stdout
+        ]
+      else
+        %w[
+          --nice
+        ]
       end
 
-      args = [
-        "--color",
-        "-I", HOMEBREW_LIBRARY_PATH/"test",
-        "--require", "spec_helper",
-        "--format", "progress",
-        "--format", "ParallelTests::RSpec::RuntimeLogger",
-        "--out", "tmp/parallel_runtime_rspec.log"
+      args = ["-I", HOMEBREW_LIBRARY_PATH/"test"]
+      args += %w[
+        --color
+        --require spec_helper
+        --format progress
+        --format ParallelTests::RSpec::RuntimeLogger
+        --out tmp/parallel_runtime_rspec.log
       ]
 
       args << "--seed" << ARGV.next if ARGV.include? "--seed"
diff --git a/Library/Homebrew/formula_installer.rb b/Library/Homebrew/formula_installer.rb
index db9115aae5..ad87c2a5fb 100644
--- a/Library/Homebrew/formula_installer.rb
+++ b/Library/Homebrew/formula_installer.rb
@@ -656,8 +656,9 @@ class FormulaInstaller
     Sandbox.print_sandbox_message if Sandbox.formula?(formula)
 
     Utils.safe_fork do
-      # Invalidate the current sudo timestamp in case a build script calls sudo
-      system "/usr/bin/sudo", "-k"
+      # Invalidate the current sudo timestamp in case a build script calls sudo.
+      # Travis CI's Linux sudoless workers have a weird sudo that fails here.
+      system "/usr/bin/sudo", "-k" unless ENV["TRAVIS_SUDO"] == "false"
 
       if Sandbox.formula?(formula)
         sandbox = Sandbox.new
diff --git a/Library/Homebrew/test/Gemfile.lock b/Library/Homebrew/test/Gemfile.lock
index 4d4eefd7d7..1f6adae933 100644
--- a/Library/Homebrew/test/Gemfile.lock
+++ b/Library/Homebrew/test/Gemfile.lock
@@ -2,51 +2,53 @@ GEM
   remote: https://rubygems.org/
   specs:
     ast (2.3.0)
-    codecov (0.1.9)
+    codecov (0.1.10)
       json
       simplecov
       url
     diff-lcs (1.3)
     docile (1.1.5)
-    json (2.0.3)
-    parallel (1.10.0)
-    parallel_tests (2.13.0)
+    json (2.1.0)
+    parallel (1.11.2)
+    parallel_tests (2.14.1)
       parallel
     parser (2.4.0.0)
       ast (~> 2.2)
     powerpack (0.1.1)
-    rainbow (2.2.1)
-    rspec (3.5.0)
-      rspec-core (~> 3.5.0)
-      rspec-expectations (~> 3.5.0)
-      rspec-mocks (~> 3.5.0)
-    rspec-core (3.5.4)
-      rspec-support (~> 3.5.0)
-    rspec-expectations (3.5.0)
+    rainbow (2.2.2)
+      rake
+    rake (12.0.0)
+    rspec (3.6.0)
+      rspec-core (~> 3.6.0)
+      rspec-expectations (~> 3.6.0)
+      rspec-mocks (~> 3.6.0)
+    rspec-core (3.6.0)
+      rspec-support (~> 3.6.0)
+    rspec-expectations (3.6.0)
       diff-lcs (>= 1.2.0, < 2.0)
-      rspec-support (~> 3.5.0)
+      rspec-support (~> 3.6.0)
     rspec-its (1.2.0)
       rspec-core (>= 3.0.0)
       rspec-expectations (>= 3.0.0)
-    rspec-mocks (3.5.0)
+    rspec-mocks (3.6.0)
       diff-lcs (>= 1.2.0, < 2.0)
-      rspec-support (~> 3.5.0)
-    rspec-support (3.5.0)
+      rspec-support (~> 3.6.0)
+    rspec-support (3.6.0)
     rspec-wait (0.0.9)
       rspec (>= 3, < 4)
-    rubocop (0.47.1)
+    rubocop (0.48.1)
       parser (>= 2.3.3.1, < 3.0)
       powerpack (~> 0.1)
       rainbow (>= 1.99.1, < 3.0)
       ruby-progressbar (~> 1.7)
       unicode-display_width (~> 1.0, >= 1.0.1)
     ruby-progressbar (1.8.1)
-    simplecov (0.13.0)
+    simplecov (0.14.1)
       docile (~> 1.1.0)
       json (>= 1.8, < 3)
       simplecov-html (~> 0.10.0)
     simplecov-html (0.10.0)
-    unicode-display_width (1.1.3)
+    unicode-display_width (1.2.1)
     url (0.3.2)
 
 PLATFORMS
@@ -62,4 +64,4 @@ DEPENDENCIES
   simplecov
 
 BUNDLED WITH
-   1.14.5
+   1.14.6