diff --git a/.travis.yml b/.travis.yml
index e4fd420..96f4c53 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -61,10 +61,13 @@ matrix:
     - env: TOOLSET=clang-3.7
     - env: TOOLSET=clang-3.8
     - env: TOOLSET=clang-3.9
-    - env: TOOLSET=clang-4.0 CXXFLAGS=-std=c++03
-    - env: TOOLSET=clang-4.0 CXXFLAGS=-std=c++11
-    - env: TOOLSET=clang-4.0 CXXFLAGS=-std=c++14
-    - env: TOOLSET=clang-4.0 CXXFLAGS=-std=c++1z
+    - env: TOOLSET=clang-4.0
+    - env: TOOLSET=clang-5.0
+    - env: TOOLSET=clang-6.0 CXXFLAGS=-std=c++03
+    - env: TOOLSET=clang-6.0 CXXFLAGS=-std=c++11
+    - env: TOOLSET=clang-6.0 CXXFLAGS=-std=c++14
+    - env: TOOLSET=clang-6.0 CXXFLAGS=-std=c++17
+    - env: TOOLSET=clang-6.0 CXXFLAGS=-std=c++2a
     - env: TOOLSET=gcc-4.7
     - env: TOOLSET=gcc-4.8
     - env: TOOLSET=gcc-4.9
diff --git a/tools/ci/library_test.py b/tools/ci/library_test.py
index a3fc55b..eb84512 100644
--- a/tools/ci/library_test.py
+++ b/tools/ci/library_test.py
@@ -92,11 +92,9 @@ class script(script_common):
             self.repo_dir = os.path.join(self.boost_root,self.repo_path)
             
         if self.repo != 'boost':
-            utils.check_call("git","submodule","update","--quiet","--init",self.repo_path)
-            if self.commit:
-                # Copy in the existing library tree checkout.
-                os.rmdir(self.repo_path)
-                shutil.copytree(self.root_dir, self.repo_path)
+            # Copy in the existing library tree checkout.
+            os.rmdir(self.repo_path)
+            shutil.copytree(self.root_dir, self.repo_path)
         
         # Fetch the dependencies for the library we are testing.
         if self.repo != 'boost':