diff --git a/lldb/packages/Python/lldbsuite/test/make/Makefile.rules b/lldb/packages/Python/lldbsuite/test/make/Makefile.rules
index be3ad684dd736..629ccee32e840 100644
--- a/lldb/packages/Python/lldbsuite/test/make/Makefile.rules
+++ b/lldb/packages/Python/lldbsuite/test/make/Makefile.rules
@@ -112,7 +112,7 @@ $(error "C compiler is not specified. Please run tests through lldb-dotest or li
 endif
 
 #----------------------------------------------------------------------
-# Handle SDKROOT on Darwin
+# Handle SDKROOT for the cross platform builds.
 #----------------------------------------------------------------------
 
 ifeq "$(OS)" "Darwin"
@@ -120,6 +120,18 @@ ifeq "$(OS)" "Darwin"
 	# We haven't otherwise set the SDKROOT, so set it now to macosx
 	SDKROOT := $(shell xcrun --sdk macosx --show-sdk-path)
     endif
+    SYSROOT_FLAGS := -isysroot "$(SDKROOT)"
+    GCC_TOOLCHAIN_FLAGS :=
+else
+    ifneq "$(SDKROOT)" ""
+        SYSROOT_FLAGS := --sysroot "$(SDKROOT)"
+        GCC_TOOLCHAIN_FLAGS := --gcc-toolchain="$(SDKROOT)/usr"
+    else
+        # Do not set up these options if SDKROOT was not specified.
+        # This is a regular build in that case (or Android).
+        SYSROOT_FLAGS :=
+        GCC_TOOLCHAIN_FLAGS :=
+    endif
 endif
 
 #----------------------------------------------------------------------
@@ -210,20 +222,15 @@ endif
 DEBUG_INFO_FLAG ?= -g
 
 CFLAGS ?= $(DEBUG_INFO_FLAG) -O0
-
-ifeq "$(OS)" "Darwin"
-	ifneq "$(SDKROOT)" ""
-		CFLAGS += -isysroot "$(SDKROOT)"
-	endif
-endif
+CFLAGS += $(SYSROOT_FLAGS)
 
 ifeq "$(OS)" "Darwin"
 	CFLAGS += $(ARCHFLAG) $(ARCH) $(FRAMEWORK_INCLUDES)
 else
 	CFLAGS += $(ARCHFLAG)$(ARCH)
 endif
-CFLAGS += -I$(LLDB_BASE_DIR)include -I$(LLDB_OBJ_ROOT)/include
 
+CFLAGS += -I$(LLDB_BASE_DIR)/include -I$(LLDB_OBJ_ROOT)/include
 CFLAGS += -I$(SRCDIR) -I$(THIS_FILE_DIR)
 
 ifndef NO_TEST_COMMON_H
@@ -234,9 +241,9 @@ CFLAGS += $(NO_LIMIT_DEBUG_INFO_FLAGS) $(ARCH_CFLAGS)
 
 # Use this one if you want to build one part of the result without debug information:
 ifeq "$(OS)" "Darwin"
-	CFLAGS_NO_DEBUG = -O0 $(ARCHFLAG) $(ARCH) $(FRAMEWORK_INCLUDES) $(ARCH_CFLAGS) $(CFLAGS_EXTRAS) -isysroot "$(SDKROOT)"
+	CFLAGS_NO_DEBUG = -O0 $(ARCHFLAG) $(ARCH) $(FRAMEWORK_INCLUDES) $(ARCH_CFLAGS) $(CFLAGS_EXTRAS) $(SYSROOT_FLAGS)
 else
-	CFLAGS_NO_DEBUG = -O0 $(ARCHFLAG)$(ARCH) $(FRAMEWORK_INCLUDES) $(ARCH_CFLAGS) $(CFLAGS_EXTRAS)
+	CFLAGS_NO_DEBUG = -O0 $(ARCHFLAG)$(ARCH) $(FRAMEWORK_INCLUDES) $(ARCH_CFLAGS) $(CFLAGS_EXTRAS) $(SYSROOT_FLAGS)
 endif
 
 ifeq "$(MAKE_DWO)" "YES"
@@ -267,7 +274,9 @@ endif
 CFLAGS += $(CFLAGS_EXTRAS)
 CXXFLAGS += -std=c++11 $(CFLAGS) $(ARCH_CXXFLAGS)
 LD = $(CC)
-LDFLAGS ?= $(CFLAGS)
+# Copy common options to the linker flags (dwarf, arch. & etc).
+# Note: we get some 'garbage' options for linker here (such as -I, --isystem & etc).
+LDFLAGS += $(CFLAGS)
 LDFLAGS += $(LD_EXTRAS) $(ARCH_LDFLAGS)
 ifeq (,$(filter $(OS), Windows_NT Android Darwin))
 	ifneq (,$(filter YES,$(ENABLE_THREADS)))
@@ -378,11 +387,26 @@ ifeq (1, $(USE_SYSTEM_STDLIB))
 	endif
 endif
 
+ifeq (,$(filter 1, $(USE_LIBSTDCPP) $(USE_LIBCPP) $(USE_SYSTEM_STDLIB)))
+  # If no explicit C++ library request was made, but we have paths to a custom libcxx, use
+  # them.  Otherwise, use the system library by default.
+  ifneq ($(and $(LIBCPP_INCLUDE_DIR), $(LIBCPP_LIBRARY_DIR)),)
+    CXXFLAGS += -nostdlib++ -nostdinc++ -cxx-isystem $(LIBCPP_INCLUDE_DIR)
+    ifneq "$(LIBCPP_INCLUDE_TARGET_DIR)" ""
+      CXXFLAGS += -cxx-isystem $(LIBCPP_INCLUDE_TARGET_DIR)
+    endif
+    LDFLAGS += -L$(LIBCPP_LIBRARY_DIR) -Wl,-rpath,$(LIBCPP_LIBRARY_DIR) -lc++
+  else
+    USE_SYSTEM_STDLIB := 1
+  endif
+endif
+
 ifeq (1,$(USE_LIBSTDCPP))
 	# Clang requires an extra flag: -stdlib=libstdc++
 	ifneq (,$(findstring clang,$(CC)))
-		CXXFLAGS += -stdlib=libstdc++
-		LDFLAGS += -stdlib=libstdc++
+		# Force clang looking for the gcc's headers at specific rootfs folder.
+		CXXFLAGS += -stdlib=libstdc++ $(GCC_TOOLCHAIN_FLAGS)
+		LDFLAGS += -stdlib=libstdc++ $(GCC_TOOLCHAIN_FLAGS)
 	endif
 endif
 
@@ -416,21 +440,15 @@ ifeq (1, $(USE_SYSTEM_STDLIB))
         endif
         CXXFLAGS += -nostdlib++ -nostdinc++ -cxx-isystem $(SDKROOT)/usr/include/c++/v1
         LDFLAGS += -L$(SDKROOT)/usr/lib -Wl,-rpath,$(SDKROOT)/usr/lib -lc++
+    else
+        ifneq (,$(findstring clang,$(CC)))
+            # Force clang looking for the gcc's headers at specific rootfs folder.
+            CXXFLAGS += $(GCC_TOOLCHAIN_FLAGS)
+            LDFLAGS += $(GCC_TOOLCHAIN_FLAGS)
+        endif
     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 $(LIBCPP_INCLUDE_DIR)
-		ifneq "$(LIBCPP_INCLUDE_TARGET_DIR)" ""
-				CXXFLAGS += -cxx-isystem $(LIBCPP_INCLUDE_TARGET_DIR)
-		endif
-		LDFLAGS += -L$(LIBCPP_LIBRARY_DIR) -Wl,-rpath,$(LIBCPP_LIBRARY_DIR) -lc++
-	endif
-endif
-
 #----------------------------------------------------------------------
 # Additional system libraries
 #----------------------------------------------------------------------