Index: libcxx/CMakeLists.txt
===================================================================
--- libcxx/CMakeLists.txt
+++ libcxx/CMakeLists.txt
@@ -448,6 +448,10 @@
 set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${LIBCXX_LIBRARY_DIR})
 set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${LIBCXX_LIBRARY_DIR})
 
+if (ZOS)
+  set(LIBCXX_DATASET_PREFIX "" CACHE STRING "Use the dataset prefix.")
+endif()
+
 # Declare libc++ configuration variables.
 # They are intended for use as follows:
 # LIBCXX_CXX_FLAGS: General flags for both the compiler and linker.
Index: libcxx/test/configs/ibm-zos-libc++-shared.cfg.in
===================================================================
--- /dev/null
+++ libcxx/test/configs/ibm-zos-libc++-shared.cfg.in
@@ -0,0 +1,45 @@
+# This testing configuration handles running the libc++ tests on
+# z/OS using a shared library.
+
+import os, site
+
+lit_config.load_config(config, '@CMAKE_CURRENT_BINARY_DIR@/cmake-bridge.cfg')
+
+config.substitutions.append(('%{flags}', ''))
+
+compile_flags = '-nostdinc++ -I %{include} -I %{libcxx}/test/support'
+if os.getenv('ZOS_LIBCXX_TEST_ASCII') == '1':
+    # Testing ASCII
+    compile_flags += ' -fzos-le-char-mode=ascii'
+else:
+    # Testing EBCDIC
+    compile_flags += ' -D_LIBCPP_HAS_NO_UNICODE'
+    config.available_features.add('zos-ebcdic')
+
+config.substitutions.append(('%{compile_flags}', compile_flags))
+
+config.substitutions.append(('%{link_flags}',
+    '-nostdlib++ -L %{install}/lib -L %{install}/libcxx/lib -lc++ -lc++_a \
+    -lc++_exception -lc++abi -lc++abixl -lunwind'))
+
+dataset_prefix = '@LIBCXX_DATASET_PREFIX@'
+if dataset_prefix is None:
+    raise ValueError('No dataset prefix has been provided.')
+
+steplib = dataset_prefix + '.SCEERUN2'
+if os.getenv('STEPLIB',''):
+    steplib += ":" + os.environ['STEPLIB']
+
+path = os.environ['PATH']
+
+config.substitutions.append(('%{exec}',
+    '%{{executor}} --execdir %T --env _BPXK_AUTOCVT=ON STEPLIB={0} PATH={1} -- '.format(steplib,path)))
+
+site.addsitedir(os.path.join('@LIBCXX_SOURCE_DIR@', 'utils'))
+import libcxx.test.params, libcxx.test.newconfig
+libcxx.test.newconfig.configure(
+    libcxx.test.params.DEFAULT_PARAMETERS,
+    libcxx.test.features.DEFAULT_FEATURES,
+    config,
+    lit_config
+)
Index: libcxxabi/test/configs/ibm-zos-libc++abi-shared.cfg.in
===================================================================
--- /dev/null
+++ libcxxabi/test/configs/ibm-zos-libc++abi-shared.cfg.in
@@ -0,0 +1,45 @@
+# Testing configuration for libc++abi on z/OS.
+
+import os, site
+
+lit_config.load_config(config, '@CMAKE_CURRENT_BINARY_DIR@/cmake-bridge.cfg')
+
+config.substitutions.append(('%{flags}',''))
+
+compile_flags = '-nostdinc++ -I %{include} -I %{cxx-include} -I %{cxx-target-include} \
+    -D_LIBCPP_ENABLE_CXX17_REMOVED_UNEXPECTED_FUNCTIONS \
+    -I %{libcxx}/test/support -I %{libcxx}/src -I %{libcxx}/include/c++build'
+
+if os.getenv('ZOS_LIBCXX_TEST_ASCII') == '1':
+    # Testing ASCII
+    compile_flags += ' -fzos-le-char-mode=ascii'
+else:
+    # Testing EBCDIC
+    compile_flags += ' -D_LIBCPP_HAS_NO_UNICODE'
+    config.available_features.add('zos-ebcdic')
+
+config.substitutions.append(('%{compile_flags}', compile_flags))
+
+config.substitutions.append(('%{link_flags}',
+    '-nostdlib++ -L %{install}/lib -L %{install}/libcxx/lib -lc++ -lc++_a \
+    -lc++_exception -lc++abi -lc++abixl -lunwind'))
+
+dataset_prefix = '@LIBCXX_DATASET_PREFIX@'
+if dataset_prefix is None:
+    raise ValueError('No dataset prefix has been provided.')
+
+steplib = dataset_prefix + '.SCEERUN2'
+if os.getenv('STEPLIB',''):
+    steplib += ":" + os.environ['STEPLIB']
+
+config.substitutions.append(('%{exec}',
+    '%{{executor}} --execdir %T --env _BPXK_AUTOCVT=ON STEPLIB={0} -- '.format(steplib)))
+
+site.addsitedir(os.path.join('@LIBCXXABI_LIBCXX_PATH@', 'utils'))
+import libcxx.test.params, libcxx.test.newconfig, libcxx.test.newconfig
+libcxx.test.newconfig.configure(
+    libcxx.test.params.DEFAULT_PARAMETERS,
+    libcxx.test.features.DEFAULT_FEATURES,
+    config,
+    lit_config
+)