diff --git a/make_helpers/build_env.mk b/make_helpers/build_env.mk
index 83093bd..a545cd0 100644
--- a/make_helpers/build_env.mk
+++ b/make_helpers/build_env.mk
@@ -1,5 +1,5 @@
 #
-# Copyright (c) 2016, ARM Limited and Contributors. All rights reserved.
+# Copyright (c) 2016-2024, Arm Limited and Contributors. All rights reserved.
 #
 # SPDX-License-Identifier: BSD-3-Clause
 #
@@ -47,7 +47,7 @@
             endif
         endif
     endif
-    include ${MAKE_HELPERS_DIRECTORY}${ENV_FILE_TO_INCLUDE}
+    include $(dir $(lastword $(MAKEFILE_LIST)))${ENV_FILE_TO_INCLUDE}
     ENV_FILE_TO_INCLUDE :=
 
     ifndef SHELL_COPY
diff --git a/make_helpers/toolchain.mk b/make_helpers/toolchain.mk
new file mode 100644
index 0000000..505630e
--- /dev/null
+++ b/make_helpers/toolchain.mk
@@ -0,0 +1,343 @@
+#
+# Copyright (c) 2023-2024, Arm Limited and Contributors. All rights reserved.
+#
+# SPDX-License-Identifier: BSD-3-Clause
+#
+
+#
+# TF-A uses three toolchains:
+#
+#   - The host toolchain (`host`) for building native tools
+#   - The AArch32 toolchain (`aarch32`) for building Arm AArch32 images
+#   - The AArch64 toolchain (`aarch64`) for building Arm AArch64 images
+#
+# In the main Makefile only one of the two Arm toolchains is enabled in any
+# given build, but individual tools and libraries may need access to both.
+#
+
+toolchains ?= host $(ARCH)
+
+ifneq ($(filter host,$(toolchains)),)
+        host-cc := $(HOSTCC)
+        host-cpp := $(HOSTCPP)
+
+        host-as := $(HOSTAS)
+
+        host-ld := $(HOSTLD)
+        host-oc := $(HOSTOC)
+        host-od := $(HOSTOD)
+        host-ar := $(HOSTAR)
+
+        host-dtc := $(HOSTDTC)
+endif
+
+ifneq ($(filter aarch32,$(toolchains)),)
+        aarch32-cc := $(if $(filter-out default,$(origin CC)),$(CC))
+        aarch32-cpp := $(if $(filter-out default,$(origin CPP)),$(CPP))
+
+        aarch32-as := $(if $(filter-out default,$(origin AS)),$(AS))
+
+        aarch32-ld := $(if $(filter-out default,$(origin LD)),$(LD))
+        aarch32-oc := $(if $(filter-out default,$(origin OC)),$(OC))
+        aarch32-od := $(if $(filter-out default,$(origin OD)),$(OD))
+        aarch32-ar := $(if $(filter-out default,$(origin AR)),$(AR))
+
+        aarch32-dtc := $(if $(filter-out default,$(origin DTC)),$(DTC))
+endif
+
+ifneq ($(filter aarch64,$(toolchains)),)
+        aarch64-cc := $(if $(filter-out default,$(origin CC)),$(CC))
+        aarch64-cpp := $(if $(filter-out default,$(origin CPP)),$(CPP))
+
+        aarch64-as := $(if $(filter-out default,$(origin AS)),$(AS))
+
+        aarch64-ld := $(if $(filter-out default,$(origin LD)),$(LD))
+        aarch64-oc := $(if $(filter-out default,$(origin OC)),$(OC))
+        aarch64-od := $(if $(filter-out default,$(origin OD)),$(OD))
+        aarch64-ar := $(if $(filter-out default,$(origin AR)),$(AR))
+
+        aarch64-dtc := $(if $(filter-out default,$(origin DTC)),$(DTC))
+endif
+
+include $(dir $(lastword $(MAKEFILE_LIST)))build_env.mk
+include $(addprefix $(dir $(lastword $(MAKEFILE_LIST)))toolchains/, \
+        $(addsuffix .mk,$(toolchains)))
+
+#
+# Configure tool classes that we recognize.
+#
+# In the context of this build system, a tool class identifies a specific role
+# or type of tool in the toolchain.
+#
+
+# C-related tools
+tool-classes := cc # C compilers
+tool-classes += cpp # C preprocessors
+
+# Assembly-related tools
+tool-classes += as # Assemblers
+
+# Linking and object-handling tools
+tool-classes += ld # Linkers
+tool-classes += oc # Object copiers
+tool-classes += od # Object dumpers
+tool-classes += ar # Archivers
+
+# Other tools
+tool-classes += dtc # Device tree compilers
+
+#
+# Configure tools that we recognize.
+#
+# Here we declare the list of specific toolchain tools that we know how to
+# interact with. We don't organize these into tool classes yet - that happens
+# further down.
+#
+
+# Arm Compiler for Embedded
+tools := arm-clang # armclang
+tools += arm-link # armlink
+tools += arm-ar # armar
+tools += arm-fromelf # fromelf
+
+# LLVM Project
+tools += llvm-clang # clang
+tools += llvm-lld # lld
+tools += llvm-objcopy # llvm-objcopy
+tools += llvm-objdump # llvm-objdump
+tools += llvm-ar # llvm-ar
+
+# GNU Compiler Collection & GNU Binary Utilities
+tools += gnu-gcc # gcc
+tools += gnu-ld # ld
+tools += gnu-objcopy # objcopy
+tools += gnu-objdump # objdump
+tools += gnu-ar # gcc-ar
+
+# Other tools
+tools += dtc # Device Tree Compiler
+
+#
+# Assign tools to tool classes.
+#
+# Multifunctional tools, i.e. tools which can perform multiple roles in a
+# toolchain, may be specified in multiple tool class lists. For example, a C
+# compiler which can also perform the role of a linker may be placed in both
+# `tools-cc` and `tools-ld`.
+#
+
+# C-related tools
+tools-cc := arm-clang llvm-clang gnu-gcc # C compilers
+tools-cpp := arm-clang llvm-clang gnu-gcc # C preprocessors
+
+# Assembly-related tools
+tools-as := arm-clang llvm-clang gnu-gcc # Assemblers
+
+# Linking and object-handling tools
+tools-ld := arm-clang arm-link llvm-clang llvm-lld gnu-gcc gnu-ld # Linkers
+tools-oc := arm-fromelf llvm-objcopy gnu-objcopy # Object copiers
+tools-od := arm-fromelf llvm-objdump gnu-objdump # Object dumpers
+tools-ar := arm-ar llvm-ar gnu-ar # Archivers
+
+# Other tools
+tools-dtc := dtc # Device tree compilers
+
+define check-tool-class-tools
+        $(eval tool-class := $(1))
+
+        ifndef tools-$(tool-class)
+                $$(error no tools registered to handle tool class `$(tool-class)`)
+        endif
+endef
+
+$(foreach tool-class,$(tool-classes), \
+        $(eval $(call check-tool-class-tools,$(tool-class))))
+
+#
+# Default tools for each toolchain.
+#
+# Toolchains can specify a default path to any given tool with a tool class.
+# These values are used in the absence of user-specified values, and are
+# configured by the parent Makefile using variables of the form:
+#
+#   - $(toolchain)-$(tool-class)-default
+#
+# For example, the default C compiler for the AArch32 and AArch64 toolchains
+# could be configured with:
+#
+#   - aarch32-cc-default
+#   - aarch64-cc-default
+#
+
+define check-toolchain-tool-class-default
+        $(eval toolchain := $(1))
+        $(eval tool-class := $(2))
+
+        ifndef $(toolchain)-$(tool-class)-default
+                $$(error no default value specified for tool class `$(tool-class)` of toolchain `$(toolchain)`)
+        endif
+endef
+
+define check-toolchain-tool-class-defaults
+        $(eval toolchain := $(1))
+
+        $(foreach tool-class,$(tool-classes), \
+                $(eval $(call check-toolchain-tool-class-default,$(toolchain),$(tool-class))))
+endef
+
+$(foreach toolchain,$(toolchains), \
+        $(eval $(call check-toolchain-tool-class-defaults,$(toolchain))))
+
+#
+# Helper functions to identify toolchain tools.
+#
+# The functions defined in this section return a tool identifier when given a
+# path to a binary. We generally check a help or version string to more reliably
+# identify tools than by looking at the path alone (e.g. `gcc` on macOS is
+# actually Apple Clang).
+#
+# Each tool-guessing function (`guess-tool-$(tool)`) takes a single argument
+# giving the path to the tool to guess, and returns a non-empty value if the
+# tool corresponds to the tool identifier `$(tool)`:
+#
+#     $(call guess-tool-llvm-clang,aarch64-none-elf-gcc) # <empty>
+#     $(call guess-tool-gnu-gcc,aarch64-none-elf-gcc) # <non-empty>
+#
+# The `guess-tool` function tries to find the corresponding tool identifier
+# for a tool given its path. It takes two arguments:
+#
+#   - $(1): a list of candidate tool identifiers to check
+#   - $(2): the path to the tool to identify
+#
+# If any of the guess functions corresponding to candidate tool identifiers
+# return a non-empty value then the tool identifier of the first function to do
+# so is returned:
+#
+#     $(call guess-tool,gnu-gcc llvm-clang,armclang) # <empty>
+#     $(call guess-tool,gnu-gcc llvm-clang,clang-14) # llvm-clang
+#     $(call guess-tool,gnu-gcc llvm-clang,aarch64-none-elf-gcc-12) # gnu-gcc
+#
+# Tools are checked in the order that they appear in `tools-$(tool-class)`, and
+# the first match is returned.
+#
+
+# Arm Compiler for Embedded
+guess-tool-arm-clang = $(shell $(1) --version 2>&1 | grep -o "Tool: armclang")
+guess-tool-arm-link = $(shell $(1) --help 2>&1 | grep -o "Tool: armlink")
+guess-tool-arm-fromelf = $(shell $(1) --help 2>&1 | grep -o "Tool: fromelf")
+guess-tool-arm-ar = $(shell $(1) --version 2>&1 | grep -o "Tool: armar")
+
+# LLVM Project
+guess-tool-llvm-clang = $(shell $(1) -v 2>&1 | grep -o "clang version")
+guess-tool-llvm-lld = $(shell $(1) --help 2>&1 | grep -o "OVERVIEW: lld")
+guess-tool-llvm-objcopy = $(shell $(1) --help 2>&1 | grep -o "llvm-objcopy tool")
+guess-tool-llvm-objdump = $(shell $(1) --help 2>&1 | grep -o "llvm object file dumper")
+guess-tool-llvm-ar = $(shell $(1) --help 2>&1 | grep -o "LLVM Archiver")
+
+# GNU Compiler Collection & GNU Binary Utilities
+guess-tool-gnu-gcc = $(shell $(1) -v 2>&1 | grep -o "gcc version")
+guess-tool-gnu-ld = $(shell $(1) -v 2>&1 | grep -o "GNU ld")
+guess-tool-gnu-objcopy = $(shell $(1) --version 2>&1 | grep -o "GNU objcopy")
+guess-tool-gnu-objdump = $(shell $(1) --version 2>&1 | grep -o "GNU objdump")
+guess-tool-gnu-ar = $(shell $(1) --version 2>&1 | grep -o "GNU ar")
+
+# Other tools
+guess-tool-dtc = $(shell $(1) --version 2>&1 | grep -o "Version: DTC")
+
+guess-tool = $(firstword $(foreach candidate,$(1), \
+        $(if $(call guess-tool-$(candidate),$(2)),$(candidate))))
+
+#
+# Locate and identify tools belonging to each toolchain.
+#
+# Each tool class in each toolchain receives a variable of the form
+# `$(toolchain)-$(tool)` giving the associated path to the program. For example:
+#
+#   - `aarch64-ld` gives the linker for the AArch64 toolchain,
+#   - `aarch32-oc` gives the object copier for the AArch32 toolchain, and
+#   - `host-cc` gives the C compiler for the host toolchain.
+#
+# For each of these variables, if no program path is explicitly provided by the
+# parent Makefile then the C compiler is queried (if supported) for its
+# location. This is done via the `guess-$(tool)-$(tool-class)` set of functions.
+# For example:
+#
+#   - `guess-arm-clang-ld` guesses the linker via Arm Clang,
+#   - `guess-llvm-clang-as` guesses the assembler via LLVM Clang, and
+#   - `guess-gnu-gcc-od` guesses the object dumper via GNU GCC.
+#
+# If the C compiler cannot provide the location (or the tool class is the C
+# compiler), then it is assigned the value of the `$(toolchain)-$(tool)-default`
+# variable.
+#
+
+guess-arm-clang-cpp = $(1) # Use the C compiler
+guess-arm-clang-as = $(1) # Use the C compiler
+guess-arm-clang-ld = # Fall back to `$(toolchain)-ld-default`
+guess-arm-clang-oc = # Fall back to `$(toolchain)-oc-default`
+guess-arm-clang-od = # Fall back to `$(toolchain)-od-default`
+guess-arm-clang-ar = # Fall back to `$(toolchain)-ar-default`
+
+guess-llvm-clang-cpp = $(1) # Use the C compiler
+guess-llvm-clang-as = $(1) # Use the C compiler
+guess-llvm-clang-ld = $(shell $(1) --print-prog-name ld.lld 2>$(nul))
+guess-llvm-clang-oc = $(shell $(1) --print-prog-name llvm-objcopy 2>$(nul))
+guess-llvm-clang-od = $(shell $(1) --print-prog-name llvm-objdump 2>$(nul))
+guess-llvm-clang-ar = $(shell $(1) --print-prog-name llvm-ar 2>$(nul))
+
+guess-gnu-gcc-cpp = $(1) # Use the C compiler
+guess-gnu-gcc-as = $(1) # Use the C compiler
+guess-gnu-gcc-ld = $(if $(filter 1,$(ENABLE_LTO)),$(1),$(shell $(1) --print-prog-name ld.bfd 2>$(nul)))
+guess-gnu-gcc-oc = $(shell $(1) --print-prog-name objcopy 2>$(nul))
+guess-gnu-gcc-od = $(shell $(1) --print-prog-name objdump 2>$(nul))
+guess-gnu-gcc-ar = $(patsubst %$(notdir $(1)),%$(subst gcc,gcc-ar,$(notdir $(1))),$(1))
+
+define locate-toolchain-tool-cc
+        $(eval toolchain := $(1))
+
+        $(toolchain)-cc := $$(strip \
+                $$(or $$($(toolchain)-cc),$$($(toolchain)-cc-default)))
+        $(toolchain)-cc-id := $$(strip \
+                $$(call guess-tool,$$(tools-cc),$$($(toolchain)-cc)))
+endef
+
+define locate-toolchain-tool
+        $(eval toolchain := $(1))
+        $(eval tool-class := $(2))
+
+        ifndef $(toolchain)-$(tool-class)
+                $(toolchain)-$(tool-class) := $$(strip \
+                        $$(call guess-$$($(toolchain)-cc-id)-$(tool-class),$$($(toolchain)-cc)))
+
+                ifeq ($$($(toolchain)-$(tool-class)),)
+                        $(toolchain)-$(tool-class) := $$(strip \
+                                $$($(toolchain)-$(tool-class)-default))
+                endif
+        endif
+
+        $(toolchain)-$(tool-class)-id := $$(strip \
+                $$(call guess-tool,$$(tools-$(tool-class)),$$($$(toolchain)-$(tool-class))))
+endef
+
+define canonicalize-toolchain-tool-path
+        $(eval toolchain := $(1))
+        $(eval tool-class := $(2))
+
+        $(toolchain)-$(tool-class) := $$(strip $$(or \
+                $$(call which,$$($(toolchain)-$(tool-class))), \
+                $$($(toolchain)-$(tool-class))))
+endef
+
+define locate-toolchain
+        $(eval toolchain := $(1))
+
+        $$(eval $$(call locate-toolchain-tool-cc,$(toolchain)))
+        $$(eval $$(call canonicalize-toolchain-tool-path,$(toolchain),cc))
+
+        $$(foreach tool-class,$$(filter-out cc,$$(tool-classes)), \
+                $$(eval $$(call locate-toolchain-tool,$(toolchain),$$(tool-class))) \
+                $$(eval $$(call canonicalize-toolchain-tool-path,$(toolchain),$$(tool-class))))
+endef
+
+$(foreach toolchain,$(toolchains), \
+        $(eval $(call locate-toolchain,$(toolchain))))
diff --git a/make_helpers/toolchains/aarch32.mk b/make_helpers/toolchains/aarch32.mk
new file mode 100644
index 0000000..226bc75
--- /dev/null
+++ b/make_helpers/toolchains/aarch32.mk
@@ -0,0 +1,14 @@
+#
+# Copyright (c) 2023-2024, Arm Limited and Contributors. All rights reserved.
+#
+# SPDX-License-Identifier: BSD-3-Clause
+#
+
+aarch32-cc-default := $(or $(CROSS_COMPILE),arm-none-eabi-)gcc
+aarch32-cpp-default := $(or $(CROSS_COMPILE),arm-none-eabi-)gcc
+aarch32-as-default := $(or $(CROSS_COMPILE),arm-none-eabi-)gcc
+aarch32-ld-default := $(or $(CROSS_COMPILE),arm-none-eabi-)ld.bfd
+aarch32-oc-default := $(or $(CROSS_COMPILE),arm-none-eabi-)objcopy
+aarch32-od-default := $(or $(CROSS_COMPILE),arm-none-eabi-)objdump
+aarch32-ar-default := $(or $(CROSS_COMPILE),arm-none-eabi-)gcc-ar
+aarch32-dtc-default := dtc
diff --git a/make_helpers/toolchains/aarch64.mk b/make_helpers/toolchains/aarch64.mk
new file mode 100644
index 0000000..15c5757
--- /dev/null
+++ b/make_helpers/toolchains/aarch64.mk
@@ -0,0 +1,14 @@
+#
+# Copyright (c) 2023-2024, Arm Limited and Contributors. All rights reserved.
+#
+# SPDX-License-Identifier: BSD-3-Clause
+#
+
+aarch64-cc-default := $(or $(CROSS_COMPILE),aarch64-none-elf-)gcc
+aarch64-cpp-default := $(or $(CROSS_COMPILE),aarch64-none-elf-)gcc
+aarch64-as-default := $(or $(CROSS_COMPILE),aarch64-none-elf-)gcc
+aarch64-ld-default := $(or $(CROSS_COMPILE),aarch64-none-elf-)ld.bfd
+aarch64-oc-default := $(or $(CROSS_COMPILE),aarch64-none-elf-)objcopy
+aarch64-od-default := $(or $(CROSS_COMPILE),aarch64-none-elf-)objdump
+aarch64-ar-default := $(or $(CROSS_COMPILE),aarch64-none-elf-)gcc-ar
+aarch64-dtc-default := dtc
diff --git a/make_helpers/toolchains/host.mk b/make_helpers/toolchains/host.mk
new file mode 100644
index 0000000..fe3fc1c
--- /dev/null
+++ b/make_helpers/toolchains/host.mk
@@ -0,0 +1,14 @@
+#
+# Copyright (c) 2023, Arm Limited and Contributors. All rights reserved.
+#
+# SPDX-License-Identifier: BSD-3-Clause
+#
+
+host-cc-default := gcc
+host-cpp-default := gcc
+host-as-default := gcc
+host-ld-default := gcc
+host-oc-default := objcopy
+host-od-default := objdump
+host-ar-default := gcc-ar
+host-dtc-default := dtc
diff --git a/make_helpers/toolchains/rk3399-m0.mk b/make_helpers/toolchains/rk3399-m0.mk
new file mode 100644
index 0000000..c61b6e8
--- /dev/null
+++ b/make_helpers/toolchains/rk3399-m0.mk
@@ -0,0 +1,14 @@
+#
+# Copyright (c) 2024, Arm Limited and Contributors. All rights reserved.
+#
+# SPDX-License-Identifier: BSD-3-Clause
+#
+
+rk3399-m0-cc-default := $(or $(M0_CROSS_COMPILE),arm-none-eabi-)gcc
+rk3399-m0-cpp-default := $(or $(M0_CROSS_COMPILE),arm-none-eabi-)gcc
+rk3399-m0-as-default := $(or $(M0_CROSS_COMPILE),arm-none-eabi-)gcc
+rk3399-m0-ld-default := $(or $(M0_CROSS_COMPILE),arm-none-eabi-)ld.bfd
+rk3399-m0-oc-default := $(or $(M0_CROSS_COMPILE),arm-none-eabi-)objcopy
+rk3399-m0-od-default := $(or $(M0_CROSS_COMPILE),arm-none-eabi-)objdump
+rk3399-m0-ar-default := $(or $(M0_CROSS_COMPILE),arm-none-eabi-)gcc-ar
+rk3399-m0-dtc-default := dtc
diff --git a/make_helpers/unix.mk b/make_helpers/unix.mk
index 545ddfd..d285799 100644
--- a/make_helpers/unix.mk
+++ b/make_helpers/unix.mk
@@ -57,4 +57,7 @@
 	-${Q}rm -rf  "${1}"
     endef
 
+    nul := /dev/null
+
+    which = $(shell which $(1) 2>$(nul))
 endif
diff --git a/make_helpers/windows.mk b/make_helpers/windows.mk
index ac0f940..980abf0 100644
--- a/make_helpers/windows.mk
+++ b/make_helpers/windows.mk
@@ -68,6 +68,9 @@
 	-@if exist "$(tmp_dir)"  rd /Q /S "$(tmp_dir)"
     endef
 
+    nul := nul
+
+    which = $(shell where $(1) 2>$(nul))
 endif
 
 # Because git is not available from CMD.EXE, we need to avoid