diff --git a/Makefile b/Makefile
index a9b3745..485e979 100644
--- a/Makefile
+++ b/Makefile
@@ -51,19 +51,25 @@
 ##
 
 # Specifies which toolchain of the prebuilt toolchains to use.
-# Can be either clang, gcc-4.9, or gcc-9.2.
+# Can be either clang, gcc-4.9 (deprecated), gcc-5.1, or gcc-9.2.
 TOOLCHAIN ?= clang
 
 # Find the toolchain path for the current OS.
 UNNAME_S := $(shell uname -s | tr '[:upper:]' '[:lower:]')
 TOOLCHAIN_CLANG := $(ROOT_DIR)/toolchains/$(UNNAME_S)-x86/clang/clang-r383902/
 TOOLCHAIN_GCC_49 := $(ROOT_DIR)/toolchains/$(UNNAME_S)-x86/gcc/aarch64-linux-gnu-4.9/
+TOOLCHAIN_GCC_51 := $(ROOT_DIR)/toolchains/$(UNNAME_S)-x86/gcc/aarch64-linux-gnu-5.1/
 TOOLCHAIN_GCC_92 := $(ROOT_DIR)/toolchains/$(UNNAME_S)-x86/gcc/aarch64-linux-gnu-9.2/
 
 # Set the toolchain build binary paths and prefixes.
 ifeq ($(TOOLCHAIN), gcc-4.9)
 TOOLCHAIN_BIN := $(TOOLCHAIN_GCC_49)/bin
 TARGET = aarch64-linux-gnu
+$(warning "The gcc-4.9 toolchain is deprecated and will be removed soon.")
+$(warning "The gcc-5.1 toolchain is the oldest version Linux needs to support.")
+else ifeq ($(TOOLCHAIN), gcc-5.1)
+TOOLCHAIN_BIN := $(TOOLCHAIN_GCC_51)/bin
+TARGET = aarch64-linux-gnu
 else ifeq ($(TOOLCHAIN), gcc-9.2)
 TOOLCHAIN_BIN := $(TOOLCHAIN_GCC_92)/bin
 TARGET = aarch64-none-linux-gnu
@@ -76,7 +82,7 @@
 TARGET = aarch64-linux-gnu
 # The GCC toolchain is needed when building kvm-unit-tests as well as Linux
 # with Clang, because of lack of support for the LLVM integrated assembler.
-GCC_TOOLCHAIN_DIR = $(TOOLCHAIN_GCC_49)
+GCC_TOOLCHAIN_DIR = $(TOOLCHAIN_GCC_51)
 GCC_TOOLCHAIN_BIN = $(GCC_TOOLCHAIN_DIR)/bin/
 LLVM = "LLVM=1"
 # Some targets require additional flags to build with Clang.