diff --git a/CMakeLists.txt b/CMakeLists.txt
index 12bbb502..3210757e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -304,6 +304,9 @@ if (LIBCXX_BUILT_STANDALONE)
       if (LLVM_USE_SANITIZER STREQUAL "MemoryWithOrigins")
         list(APPEND LIBCXX_CXX_FEATURE_FLAGS "-fsanitize-memory-track-origins")
       endif()
+    elseif (LLVM_USE_SANITIZER STREQUAL "Undefined")
+      list(APPEND LIBCXX_CXX_FEATURE_FLAGS
+          "-fsanitize=undefined -fno-sanitize=vptr,function -fno-sanitize-recover")
     else()
       message(WARNING "Unsupported value of LLVM_USE_SANITIZER: ${LLVM_USE_SANITIZER}")
     endif()
diff --git a/test/lit.cfg b/test/lit.cfg
index bed329fe..fbeb8275 100644
--- a/test/lit.cfg
+++ b/test/lit.cfg
@@ -434,6 +434,11 @@ class Configuration(object):
                 if san == 'MemoryWithOrigins':
                     self.compile_flags += ['-fsanitize-memory-track-origins']
                 self.config.available_features.add('msan')
+            elif san == 'Undefined':
+                self.compile_flags += ['-fsanitize=undefined',
+                                       '-fno-sanitize=vptr,function',
+                                       '-fno-sanitize-recover']
+                self.config.available_features.add('ubsan')
             else:
                 self.lit_config.fatal('unsupported value for '
                                       'libcxx_use_san: {0}'.format(san))