diff --git a/lldb/test/API/lit.cfg.py b/lldb/test/API/lit.cfg.py
--- a/lldb/test/API/lit.cfg.py
+++ b/lldb/test/API/lit.cfg.py
@@ -171,10 +171,11 @@
   dotest_cmd += ['--env', 'LLVM_TOOLS_DIR=' + config.llvm_tools_dir]
 
 # If we have a just-built libcxx, prefer it over the system one.
-if is_configured('has_libcxx') and platform.system() != 'Windows':
-  if is_configured('llvm_include_dir') and is_configured('llvm_libs_dir'):
-    dotest_cmd += ['--libcxx-include-dir', os.path.join(config.llvm_include_dir, 'c++', 'v1')]
-    dotest_cmd += ['--libcxx-library-dir', config.llvm_libs_dir]
+if is_configured('has_libcxx') and config.has_libcxx:
+  if platform.system() != 'Windows':
+    if is_configured('llvm_include_dir') and is_configured('llvm_libs_dir'):
+      dotest_cmd += ['--libcxx-include-dir', os.path.join(config.llvm_include_dir, 'c++', 'v1')]
+      dotest_cmd += ['--libcxx-library-dir', config.llvm_libs_dir]
 
 # Forward ASan-specific environment variables to tests, as a test may load an
 # ASan-ified dylib.
diff --git a/lldb/test/API/lit.site.cfg.py.in b/lldb/test/API/lit.site.cfg.py.in
--- a/lldb/test/API/lit.site.cfg.py.in
+++ b/lldb/test/API/lit.site.cfg.py.in
@@ -31,7 +31,7 @@
 config.test_arch = '@LLDB_TEST_ARCH@'
 config.test_compiler = lit_config.substitute('@LLDB_TEST_COMPILER@')
 config.dsymutil = lit_config.substitute('@LLDB_TEST_DSYMUTIL@')
-config.has_libcxx = '@LLDB_HAS_LIBCXX@'
+config.has_libcxx = @LLDB_HAS_LIBCXX@
 # The API tests use their own module caches.
 config.lldb_module_cache = os.path.join("@LLDB_TEST_MODULE_CACHE_LLDB@", "lldb-api")
 config.clang_module_cache = os.path.join("@LLDB_TEST_MODULE_CACHE_CLANG@", "lldb-api")