Index: packages/Python/lldbsuite/test/lang/objc/modules-auto-import/Makefile
===================================================================
--- packages/Python/lldbsuite/test/lang/objc/modules-auto-import/Makefile
+++ packages/Python/lldbsuite/test/lang/objc/modules-auto-import/Makefile
@@ -1,6 +1,6 @@
 LEVEL = ../../../make
 OBJC_SOURCES := main.m
 
-CFLAGS += -fmodules -gmodules -g
+CFLAGS += -gmodules $(MANDATORY_MODULE_BUILD_CFLAGS)
 
 include $(LEVEL)/Makefile.rules
Index: packages/Python/lldbsuite/test/lang/objc/modules-incomplete/Makefile
===================================================================
--- packages/Python/lldbsuite/test/lang/objc/modules-incomplete/Makefile
+++ packages/Python/lldbsuite/test/lang/objc/modules-incomplete/Makefile
@@ -4,5 +4,5 @@
 
 include $(LEVEL)/Makefile.rules
 
-CFLAGS += -fmodules -I$(PWD)
+CFLAGS += $(MANDATORY_MODULE_BUILD_CFLAGS) -I$(PWD)
 LDFLAGS += -framework Foundation
Index: packages/Python/lldbsuite/test/lang/objc/modules-inline-functions/Makefile
===================================================================
--- packages/Python/lldbsuite/test/lang/objc/modules-inline-functions/Makefile
+++ packages/Python/lldbsuite/test/lang/objc/modules-inline-functions/Makefile
@@ -6,4 +6,4 @@
 
 include $(LEVEL)/Makefile.rules
 
-CFLAGS += -fmodules -I$(PWD)
+CFLAGS += $(MANDATORY_MODULE_BUILD_CFLAGS) -I$(PWD)
Index: packages/Python/lldbsuite/test/make/Makefile.rules
===================================================================
--- packages/Python/lldbsuite/test/make/Makefile.rules
+++ packages/Python/lldbsuite/test/make/Makefile.rules
@@ -237,13 +237,15 @@
 	CFLAGS += -gsplit-dwarf
 endif
 
+CLANG_MODULE_CACHE_DIR := module-cache
+
+MANDATORY_MODULE_BUILD_CFLAGS := -fmodules -fmodules-cache-path=$(CLANG_MODULE_CACHE_DIR)
+
 ifeq "$(MAKE_GMODULES)" "YES"
-	CFLAGS += -fmodules -gmodules
+	CFLAGS += -gmodules $(MANDATORY_MODULE_BUILD_CFLAGS)
 endif
 
-CXXFLAGS += -std=c++11
-# FIXME: C++ modules aren't supported on all platforms.
-CXXFLAGS += $(subst -fmodules,, $(CFLAGS))
+CXXFLAGS += -std=c++11 $(CFLAGS)
 LD = $(CC)
 LDFLAGS ?= $(CFLAGS)
 LDFLAGS += $(LD_EXTRAS) $(ARCH_LDFLAGS)
@@ -636,7 +638,7 @@
 dsym:	$(DSYM)
 all:	$(EXE) $(DSYM)
 clean::
-	$(RM) $(OBJECTS) $(PREREQS) $(PREREQS:.d=.d.tmp) $(DWOS) $(ARCHIVE_NAME) $(ARCHIVE_OBJECTS)
+	$(RM) -rf $(OBJECTS) $(PREREQS) $(PREREQS:.d=.d.tmp) $(DWOS) $(ARCHIVE_NAME) $(ARCHIVE_OBJECTS) $(CLANG_MODULE_CACHE_DIR)
 ifneq "$(DYLIB_NAME)" ""
 	$(RM) -r $(DYLIB_FILENAME).dSYM
 	$(RM) $(DYLIB_OBJECTS) $(DYLIB_PREREQS) $(DYLIB_PREREQS:.d=.d.tmp) $(DYLIB_DWOS) $(DYLIB_FILENAME) $(DYLIB_FILENAME).debug