diff --git a/lldb/packages/Python/lldbsuite/test/make/Makefile.rules b/lldb/packages/Python/lldbsuite/test/make/Makefile.rules
index 937a2ae06fc44..c0fd5ecd0dc84 100644
--- a/lldb/packages/Python/lldbsuite/test/make/Makefile.rules
+++ b/lldb/packages/Python/lldbsuite/test/make/Makefile.rules
@@ -387,6 +387,16 @@ endif
 #----------------------------------------------------------------------
 # C++ standard library options
 #----------------------------------------------------------------------
+ifneq ($(and $(USE_LIBSTDCPP), $(USE_LIBCPP)),)
+	$(error Libcxx and Libstdc++ cannot be used together)
+endif
+
+ifeq (1, $(USE_SYSTEM_STDLIB))
+	ifneq ($(or $(USE_LIBSTDCPP), $(USE_LIBCPP)),)
+		$(error Cannot use system's standard library and a custom standard library together)
+	endif
+endif
+
 ifeq (1,$(USE_LIBSTDCPP))
 	# Clang requires an extra flag: -stdlib=libstdc++
 	ifneq (,$(findstring clang,$(CC)))
@@ -415,6 +425,15 @@ ifeq (1,$(USE_LIBCPP))
 	endif
 endif
 
+# If no explicit request was made, but we have paths to a custom libcxx, use
+# them.
+ifeq ($(or $(USE_LIBSTDCPP), $(USE_LIBCPP), $(USE_SYSTEM_STDLIB)),)
+	ifneq ($(and $(LIBCPP_INCLUDE_DIR), $(LIBCPP_LIBRARY_DIR)),)
+		CXXFLAGS += -nostdlib++ -nostdinc++ -cxx-isystem $(LIBCPP_INCLUDE_DIR)
+		LDFLAGS += -L$(LLVM_LIBS_DIR) -Wl,-rpath,$(LIBCPP_LIBRARY_DIR) -lc++
+	endif
+endif
+
 #----------------------------------------------------------------------
 # Additional system libraries
 #----------------------------------------------------------------------
diff --git a/lldb/test/API/commands/expression/fixits/TestFixIts.py b/lldb/test/API/commands/expression/fixits/TestFixIts.py
index bf4118d1b9d86..bcc7e61d5261c 100644
--- a/lldb/test/API/commands/expression/fixits/TestFixIts.py
+++ b/lldb/test/API/commands/expression/fixits/TestFixIts.py
@@ -45,7 +45,7 @@ def test_with_target(self):
 
         # Try with one error in a top-level expression.
         # The Fix-It changes "ptr.m" to "ptr->m".
-        expr = "struct X { int m; }; X x; X *ptr = &x; int m = ptr.m;"
+        expr = "struct MyTy { int m; }; MyTy x; MyTy *ptr = &x; int m = ptr.m;"
         value = frame.EvaluateExpression(expr, top_level_options)
         # A successfully parsed top-level expression will yield an error
         # that there is 'no value'. If a parsing error would have happened we
diff --git a/lldb/test/API/commands/expression/import-std-module/forward_list-dbg-info-content/TestDbgInfoContentForwardListFromStdModule.py b/lldb/test/API/commands/expression/import-std-module/forward_list-dbg-info-content/TestDbgInfoContentForwardListFromStdModule.py
index f9b7219c72a3d..d794f3b127b3a 100644
--- a/lldb/test/API/commands/expression/import-std-module/forward_list-dbg-info-content/TestDbgInfoContentForwardListFromStdModule.py
+++ b/lldb/test/API/commands/expression/import-std-module/forward_list-dbg-info-content/TestDbgInfoContentForwardListFromStdModule.py
@@ -29,8 +29,3 @@ def test(self):
         self.expect_expr("std::distance(a.begin(), a.end())", result_value="3")
         self.expect_expr("a.front().a", result_type="int", result_value="3")
         self.expect_expr("a.begin()->a", result_type="int", result_value="3")
-
-        # FIXME: The value here isn't actually empty.
-        self.expect_expr("a.front()",
-                         result_type=value_type,
-                         result_children=[ValueCheck()])
diff --git a/lldb/test/API/lang/objc/exceptions/Makefile b/lldb/test/API/lang/objc/exceptions/Makefile
index 876340159d9c8..355010a867e3a 100644
--- a/lldb/test/API/lang/objc/exceptions/Makefile
+++ b/lldb/test/API/lang/objc/exceptions/Makefile
@@ -2,7 +2,7 @@ OBJCXX_SOURCES := main.mm
 
 CFLAGS_EXTRAS := -w
 
-
+USE_SYSTEM_STDLIB := 1
 
 LD_EXTRAS := -framework Foundation
 include Makefile.rules
diff --git a/lldb/test/API/macosx/macCatalyst/Makefile b/lldb/test/API/macosx/macCatalyst/Makefile
index d162c33d774f9..3f084968a2d57 100644
--- a/lldb/test/API/macosx/macCatalyst/Makefile
+++ b/lldb/test/API/macosx/macCatalyst/Makefile
@@ -3,6 +3,8 @@ C_SOURCES := main.c
 override TRIPLE := $(ARCH)-apple-ios13.1-macabi
 CFLAGS_EXTRAS := -target $(TRIPLE)
 
+USE_SYSTEM_STDLIB := 1
+
 # FIXME: rdar://problem/54986190
 # There is a Clang driver change missing on llvm.org.
 override CC=xcrun clang
diff --git a/lldb/test/API/python_api/sbmodule/TestSBModule.py b/lldb/test/API/python_api/sbmodule/TestSBModule.py
index 046c9abddd18c..5a6a8e99ebfe3 100644
--- a/lldb/test/API/python_api/sbmodule/TestSBModule.py
+++ b/lldb/test/API/python_api/sbmodule/TestSBModule.py
@@ -47,8 +47,8 @@ def test_module_is_file_backed(self):
         process = target.AttachToProcessWithID(self.dbg.GetListener(),
                                                self.background_pid, error)
         self.assertTrue(error.Success() and process,  PROCESS_IS_VALID)
-        main_module = target.GetModuleAtIndex(0)
-        self.assertEqual(main_module.GetFileSpec().GetFilename(), "a.out")
+        main_module = target.FindModule(lldb.SBFileSpec("a.out"))
+        self.assertTrue(main_module is not None)
         self.assertFalse(main_module.IsFileBacked(),
                          "The module should not be backed by a file on disk.")
 
diff --git a/lldb/test/API/tools/lldb-server/TestAppleSimulatorOSType.py b/lldb/test/API/tools/lldb-server/TestAppleSimulatorOSType.py
index 1f3afb1d404ce..e666f34bf6068 100644
--- a/lldb/test/API/tools/lldb-server/TestAppleSimulatorOSType.py
+++ b/lldb/test/API/tools/lldb-server/TestAppleSimulatorOSType.py
@@ -70,6 +70,7 @@ def check_simulator_ostype(self, sdk, platform_name, arch=platform.machine()):
                 'SDKROOT': sdkroot.strip(),
                 'ARCH': arch,
                 'ARCH_CFLAGS': '-target {} {}'.format(triple, version_min),
+                'USE_SYSTEM_STDLIB': 1,
             })
         exe_path = os.path.realpath(self.getBuildArtifact(exe_name))
         cmd = [