diff --git a/Kconfig.zephyr b/Kconfig.zephyr
index d8df86add4d39..3b3ceec358431 100644
--- a/Kconfig.zephyr
+++ b/Kconfig.zephyr
@@ -481,7 +481,9 @@ choice COMPILER_OPTIMIZATIONS
 	prompt "Optimization level"
 	default NO_OPTIMIZATIONS    if COVERAGE
 	default DEBUG_OPTIMIZATIONS if DEBUG
-	default SIZE_OPTIMIZATIONS_AGGRESSIVE if "$(ZEPHYR_TOOLCHAIN_VARIANT)" = "llvm"
+	# gcc 14.3 -Os is broken on riscv. This setting should be in the SDK, it's here for testing
+	default SPEED_OPTIMIZATIONS if "$(TOOLCHAIN_VARIANT_COMPILER)" = "gnu" && RISCV
+	default SIZE_OPTIMIZATIONS_AGGRESSIVE if "$(TOOLCHAIN_VARIANT_COMPILER)" = "llvm"
 	default SIZE_OPTIMIZATIONS
 	help
 	  Note that these flags shall only control the compiler
diff --git a/cmake/compiler/clang/compiler_flags.cmake b/cmake/compiler/clang/compiler_flags.cmake
index 20bee6d4f3b09..60c494b40dfc9 100644
--- a/cmake/compiler/clang/compiler_flags.cmake
+++ b/cmake/compiler/clang/compiler_flags.cmake
@@ -3,6 +3,15 @@ include(${ZEPHYR_BASE}/cmake/compiler/gcc/compiler_flags.cmake)
 
 # Now, let's overwrite the flags that are different in clang.
 
+set_property(TARGET compiler-cpp PROPERTY dialect_cpp2a "-std=c++2a"
+  "-Wno-register" "-Wno-deprecated-volatile")
+set_property(TARGET compiler-cpp PROPERTY dialect_cpp20 "-std=c++20"
+  "-Wno-register" "-Wno-deprecated-volatile")
+set_property(TARGET compiler-cpp PROPERTY dialect_cpp2b "-std=c++2b"
+  "-Wno-register" "-Wno-deprecated-volatile")
+set_property(TARGET compiler-cpp PROPERTY dialect_cpp23 "-std=c++23"
+  "-Wno-register" "-Wno-deprecated-volatile")
+
 # No property flag, clang doesn't understand fortify at all
 set_compiler_property(PROPERTY security_fortify_compile_time)
 set_compiler_property(PROPERTY security_fortify_run_time)
diff --git a/cmake/linker/lld/linker_libraries.cmake b/cmake/linker/lld/linker_libraries.cmake
index 8275d779337fd..2a73ed4a01323 100644
--- a/cmake/linker/lld/linker_libraries.cmake
+++ b/cmake/linker/lld/linker_libraries.cmake
@@ -16,4 +16,8 @@ if(CONFIG_CPP
   set_property(TARGET linker PROPERTY link_order_library "c++")
 endif()
 
-set_property(TARGET linker APPEND PROPERTY link_order_library "c;rt")
+if(NOT CONFIG_MINIMAL_LIBC)
+  set_property(TARGET linker APPEND PROPERTY link_order_library "c")
+endif()
+
+set_property(TARGET linker APPEND PROPERTY link_order_library "rt")
diff --git a/cmake/modules/FindHostTools.cmake b/cmake/modules/FindHostTools.cmake
index a73d52956aafd..ab7abf6cceefe 100644
--- a/cmake/modules/FindHostTools.cmake
+++ b/cmake/modules/FindHostTools.cmake
@@ -73,7 +73,7 @@ endif()
 # Default to the host system's toolchain if we are targeting a host based target
 if((${BOARD_DIR} MATCHES "boards\/native") OR ("${ARCH}" STREQUAL "posix")
    OR ("${BOARD}" STREQUAL "unit_testing"))
-  if(NOT "${ZEPHYR_TOOLCHAIN_VARIANT}" STREQUAL "llvm")
+  if(NOT "${ZEPHYR_TOOLCHAIN_VARIANT}" STREQUAL "host/llvm")
     set(ZEPHYR_TOOLCHAIN_VARIANT "host")
   endif()
 endif()
@@ -95,15 +95,24 @@ zephyr_file(APPLICATION_ROOT TOOLCHAIN_ROOT)
 
 # Host-tools don't unconditionally set TOOLCHAIN_HOME anymore,
 # but in case Zephyr's SDK toolchain is used, set TOOLCHAIN_HOME
-if("${ZEPHYR_TOOLCHAIN_VARIANT}" STREQUAL "zephyr")
+if("${ZEPHYR_TOOLCHAIN_VARIANT}" MATCHES "^zephyr/?")
   set(TOOLCHAIN_HOME ${HOST_TOOLS_HOME})
 endif()
 
 set(TOOLCHAIN_ROOT ${TOOLCHAIN_ROOT} CACHE STRING "Zephyr toolchain root" FORCE)
 assert(TOOLCHAIN_ROOT "Zephyr toolchain root path invalid: please set the TOOLCHAIN_ROOT-variable")
 
+
+# Check if ZEPHYR_TOOLCHAIN_VARIANT follows "<variant_name>/<compiler>" pattern
+if("${ZEPHYR_TOOLCHAIN_VARIANT}" MATCHES "^([^/]+)/([^/]+)$")
+  set(_variant "${CMAKE_MATCH_1}")
+  set(_compiler "${CMAKE_MATCH_2}")
+  set(ZEPHYR_TOOLCHAIN_VARIANT "${_variant}")
+  set(TOOLCHAIN_VARIANT_COMPILER ${_compiler} CACHE STRING "compiler used by the toolchain variant" FORCE)
+endif()
+
 # Set cached ZEPHYR_TOOLCHAIN_VARIANT.
-set(ZEPHYR_TOOLCHAIN_VARIANT ${ZEPHYR_TOOLCHAIN_VARIANT} CACHE STRING "Zephyr toolchain variant")
+set(ZEPHYR_TOOLCHAIN_VARIANT ${ZEPHYR_TOOLCHAIN_VARIANT} CACHE STRING "Zephyr toolchain variant" FORCE)
 
 # Configure the toolchain based on what SDK/toolchain is in use.
 include(${TOOLCHAIN_ROOT}/cmake/toolchain/${ZEPHYR_TOOLCHAIN_VARIANT}/generic.cmake)
diff --git a/cmake/modules/FindZephyr-sdk.cmake b/cmake/modules/FindZephyr-sdk.cmake
index 90bbed017ce68..c85b93a5a29b0 100644
--- a/cmake/modules/FindZephyr-sdk.cmake
+++ b/cmake/modules/FindZephyr-sdk.cmake
@@ -54,7 +54,7 @@ endif()
 # 1) Zephyr specified as toolchain (ZEPHYR_SDK_INSTALL_DIR still used if defined)
 # 2) No toolchain specified == Default to Zephyr toolchain
 # Until we completely deprecate it
-if(("zephyr" STREQUAL ${ZEPHYR_TOOLCHAIN_VARIANT}) OR
+if((${ZEPHYR_TOOLCHAIN_VARIANT} MATCHES "^zephyr/?") OR
    (NOT DEFINED ZEPHYR_TOOLCHAIN_VARIANT) OR
    (DEFINED ZEPHYR_SDK_INSTALL_DIR) OR
    (Zephyr-sdk_FIND_REQUIRED))
diff --git a/cmake/modules/kconfig.cmake b/cmake/modules/kconfig.cmake
index de87abfdc1d3a..7f66dcc5a9a9a 100644
--- a/cmake/modules/kconfig.cmake
+++ b/cmake/modules/kconfig.cmake
@@ -129,6 +129,18 @@ else()
   set(_local_TOOLCHAIN_HAS_PICOLIBC n)
 endif()
 
+if(TOOLCHAIN_HAS_GLIBCXX)
+  set(_local_TOOLCHAIN_HAS_GLIBCXX y)
+else()
+  set(_local_TOOLCHAIN_HAS_GLIBCXX n)
+endif()
+
+if(TOOLCHAIN_HAS_LIBCXX)
+  set(_local_TOOLCHAIN_HAS_LIBCXX y)
+else()
+  set(_local_TOOLCHAIN_HAS_LIBCXX n)
+endif()
+
 # APP_DIR: Path to the main image (sysbuild) or synonym for APPLICATION_SOURCE_DIR (non-sysbuild)
 zephyr_get(APP_DIR VAR APP_DIR APPLICATION_SOURCE_DIR)
 
@@ -151,9 +163,12 @@ set(COMMON_KCONFIG_ENV_SETTINGS
   KCONFIG_BINARY_DIR=${KCONFIG_BINARY_DIR}
   APPLICATION_SOURCE_DIR=${APPLICATION_SOURCE_DIR}
   ZEPHYR_TOOLCHAIN_VARIANT=${ZEPHYR_TOOLCHAIN_VARIANT}
+  TOOLCHAIN_VARIANT_COMPILER=${TOOLCHAIN_VARIANT_COMPILER}
   TOOLCHAIN_KCONFIG_DIR=${TOOLCHAIN_KCONFIG_DIR}
   TOOLCHAIN_HAS_NEWLIB=${_local_TOOLCHAIN_HAS_NEWLIB}
   TOOLCHAIN_HAS_PICOLIBC=${_local_TOOLCHAIN_HAS_PICOLIBC}
+  TOOLCHAIN_HAS_GLIBCXX=${_local_TOOLCHAIN_HAS_GLIBCXX}
+  TOOLCHAIN_HAS_LIBCXX=${_local_TOOLCHAIN_HAS_LIBCXX}
   EDT_PICKLE=${EDT_PICKLE}
   # Export all Zephyr modules to Kconfig
   ${ZEPHYR_KCONFIG_MODULES_DIR}
diff --git a/cmake/toolchain/espressif/generic.cmake b/cmake/toolchain/espressif/generic.cmake
index a1e892f5a1525..114fbb42a4e5e 100644
--- a/cmake/toolchain/espressif/generic.cmake
+++ b/cmake/toolchain/espressif/generic.cmake
@@ -54,3 +54,4 @@ if(NOT CROSS_COMPILE_TARGET)
 endif()
 
 set(TOOLCHAIN_HAS_NEWLIB ON CACHE BOOL "True if toolchain supports newlib")
+set(TOOLCHAIN_HAS_GLIBCXX ON CACHE BOOL "True if toolchain supports libstdc++")
diff --git a/cmake/toolchain/gnuarmemb/generic.cmake b/cmake/toolchain/gnuarmemb/generic.cmake
index db59e5fc70757..3b8afb7c5ae1c 100644
--- a/cmake/toolchain/gnuarmemb/generic.cmake
+++ b/cmake/toolchain/gnuarmemb/generic.cmake
@@ -18,6 +18,8 @@ set(SYSROOT_TARGET       arm-none-eabi)
 
 set(CROSS_COMPILE ${TOOLCHAIN_HOME}/bin/${CROSS_COMPILE_TARGET}-)
 set(SYSROOT_DIR   ${TOOLCHAIN_HOME}/${SYSROOT_TARGET})
+
 set(TOOLCHAIN_HAS_NEWLIB ON CACHE BOOL "True if toolchain supports newlib")
+set(TOOLCHAIN_HAS_GLIBCXX ON CACHE BOOL "True if toolchain supports libstdc++")
 
 message(STATUS "Found toolchain: gnuarmemb (${GNUARMEMB_TOOLCHAIN_PATH})")
diff --git a/cmake/toolchain/host/generic.cmake b/cmake/toolchain/host/generic.cmake
index 29d67535ea6a6..878343695f557 100644
--- a/cmake/toolchain/host/generic.cmake
+++ b/cmake/toolchain/host/generic.cmake
@@ -1,9 +1,20 @@
 # SPDX-License-Identifier: Apache-2.0
 
-set(COMPILER host-gcc)
-set(LINKER ld)
-set(BINTOOLS host-gnu)
+if(TOOLCHAIN_VARIANT_COMPILER STREQUAL "gnu" OR
+    NOT DEFINED TOOLCHAIN_VARIANT_COMPILER)
 
-set(TOOLCHAIN_HAS_NEWLIB OFF CACHE BOOL "True if toolchain supports newlib")
+  if (NOT DEFINED TOOLCHAIN_VARIANT_COMPILER)
+    set(TOOLCHAIN_VARIANT_COMPILER "gnu" CACHE STRING "compiler used by the toolchain variant" FORCE)
+  endif()
+
+  include(${ZEPHYR_BASE}/cmake/toolchain/host/gnu/generic.cmake)
+
+  set(TOOLCHAIN_KCONFIG_DIR ${ZEPHYR_BASE}/cmake/toolchain/host/gnu)
+  set(TOOLCHAIN_HAS_NEWLIB OFF CACHE BOOL "True if toolchain supports newlib")
+  set(TOOLCHAIN_HAS_GLIBCXX ON CACHE BOOL "True if toolchain supports libstdc++")
+elseif(TOOLCHAIN_VARIANT_COMPILER STREQUAL "llvm")
+
+  include(${ZEPHYR_BASE}/cmake/toolchain/host/llvm/generic.cmake)
+  set(TOOLCHAIN_KCONFIG_DIR ${ZEPHYR_BASE}/cmake/toolchain/host/llvm)
+endif()
 
-message(STATUS "Found toolchain: host (gcc/ld)")
diff --git a/cmake/toolchain/host/Kconfig b/cmake/toolchain/host/gnu/Kconfig
similarity index 75%
rename from cmake/toolchain/host/Kconfig
rename to cmake/toolchain/host/gnu/Kconfig
index 81958491352db..8e5f543e03f6c 100644
--- a/cmake/toolchain/host/Kconfig
+++ b/cmake/toolchain/host/gnu/Kconfig
@@ -1,6 +1,7 @@
-# Copyright (c) 2024 Basalte bv
+# Copyright The Zephyr Project Contributors
 # SPDX-License-Identifier: Apache-2.0
 
 config TOOLCHAIN_HOST_SUPPORTS_GNU_EXTENSIONS
 	def_bool y
 	select TOOLCHAIN_SUPPORTS_GNU_EXTENSIONS
+
diff --git a/cmake/toolchain/host/gnu/generic.cmake b/cmake/toolchain/host/gnu/generic.cmake
new file mode 100644
index 0000000000000..90a0e720da7b2
--- /dev/null
+++ b/cmake/toolchain/host/gnu/generic.cmake
@@ -0,0 +1,9 @@
+
+set(TOOLCHAIN_VARIANT_COMPILER gcc CACHE STRING "Variant compiler being used")
+set(COMPILER host-gcc)
+set(LINKER ld)
+set(BINTOOLS host-gnu)
+
+set(TOOLCHAIN_HAS_NEWLIB OFF CACHE BOOL "True if toolchain supports newlib")
+
+message(STATUS "Found toolchain: host (gcc/ld)")
diff --git a/cmake/toolchain/host/gnu/target.cmake b/cmake/toolchain/host/gnu/target.cmake
new file mode 100644
index 0000000000000..9881313609aae
--- /dev/null
+++ b/cmake/toolchain/host/gnu/target.cmake
@@ -0,0 +1 @@
+# SPDX-License-Identifier: Apache-2.0
diff --git a/cmake/toolchain/llvm/Kconfig b/cmake/toolchain/host/llvm/Kconfig
similarity index 85%
rename from cmake/toolchain/llvm/Kconfig
rename to cmake/toolchain/host/llvm/Kconfig
index 00ef90d7da363..39cfcb9c1026c 100644
--- a/cmake/toolchain/llvm/Kconfig
+++ b/cmake/toolchain/host/llvm/Kconfig
@@ -1,9 +1,9 @@
-# Copyright (c) 2023 Intel Corporation
+# Copyright The Zephyr Project Contributors
+# Copyright (c) 2024 Basalte bv
 # SPDX-License-Identifier: Apache-2.0
-
+#
 choice LLVM_LINKER
 	prompt "LLVM Linker"
-	depends on "${ZEPHYR_TOOLCHAIN_VARIANT}" = "llvm"
 	default LLVM_USE_LD
 
 config LLVM_USE_LD
diff --git a/cmake/toolchain/llvm/clang_compiler_rt.cfg b/cmake/toolchain/host/llvm/clang_compiler_rt.cfg
similarity index 100%
rename from cmake/toolchain/llvm/clang_compiler_rt.cfg
rename to cmake/toolchain/host/llvm/clang_compiler_rt.cfg
diff --git a/cmake/toolchain/llvm/clang_libgcc.cfg b/cmake/toolchain/host/llvm/clang_libgcc.cfg
similarity index 100%
rename from cmake/toolchain/llvm/clang_libgcc.cfg
rename to cmake/toolchain/host/llvm/clang_libgcc.cfg
diff --git a/cmake/toolchain/llvm/generic.cmake b/cmake/toolchain/host/llvm/generic.cmake
similarity index 87%
rename from cmake/toolchain/llvm/generic.cmake
rename to cmake/toolchain/host/llvm/generic.cmake
index f6d7878288db5..db282001f9e5a 100644
--- a/cmake/toolchain/llvm/generic.cmake
+++ b/cmake/toolchain/host/llvm/generic.cmake
@@ -1,11 +1,7 @@
-# SPDX-License-Identifier: Apache-2.0
-
-# Purpose of the generic.cmake is to define a generic C compiler which can be
-# used for devicetree pre-processing and other pre-processing tasks which must
-# be performed before the target can be determined.
 
 # Todo: deprecate CLANG_ROOT_DIR
 set_ifndef(LLVM_TOOLCHAIN_PATH "$ENV{CLANG_ROOT_DIR}")
+set(TOOLCHAIN_VARIANT_COMPILER llvm CACHE STRING "Variant compiler being used")
 zephyr_get(LLVM_TOOLCHAIN_PATH)
 
 if(LLVM_TOOLCHAIN_PATH)
@@ -41,4 +37,6 @@ if(NOT LLVM_TOOLCHAIN_PATH STREQUAL "")
   endif()
 endif()
 
+set(TOOLCHAIN_HAS_LIBCXX ON CACHE BOOL "True if toolchain supports libc++")
+
 message(STATUS "Found toolchain: llvm (clang/ld)")
diff --git a/cmake/toolchain/llvm/target.cmake b/cmake/toolchain/host/llvm/target.cmake
similarity index 87%
rename from cmake/toolchain/llvm/target.cmake
rename to cmake/toolchain/host/llvm/target.cmake
index d8684ef53d07c..1313cb1efd342 100644
--- a/cmake/toolchain/llvm/target.cmake
+++ b/cmake/toolchain/host/llvm/target.cmake
@@ -55,5 +55,7 @@ elseif(CONFIG_COMPILER_RT_RTLIB)
   set(runtime_lib "compiler_rt")
 endif()
 
-list(APPEND TOOLCHAIN_C_FLAGS --config=${ZEPHYR_BASE}/cmake/toolchain/llvm/clang_${runtime_lib}.cfg)
-list(APPEND TOOLCHAIN_LD_FLAGS --config=${ZEPHYR_BASE}/cmake/toolchain/llvm/clang_${runtime_lib}.cfg)
+list(APPEND TOOLCHAIN_C_FLAGS
+     --config=${ZEPHYR_BASE}/cmake/toolchain/host/llvm/clang_${runtime_lib}.cfg)
+list(APPEND TOOLCHAIN_LD_FLAGS
+     --config=${ZEPHYR_BASE}/cmake/toolchain/host/llvm/clang_${runtime_lib}.cfg)
diff --git a/cmake/toolchain/host/target.cmake b/cmake/toolchain/host/target.cmake
index 5a1a0e51313ac..f334afeaf9d24 100644
--- a/cmake/toolchain/host/target.cmake
+++ b/cmake/toolchain/host/target.cmake
@@ -1,3 +1,10 @@
 # SPDX-License-Identifier: Apache-2.0
 
-# This file intentionally left blank.
+if(TOOLCHAIN_VARIANT_COMPILER STREQUAL "gnu" OR
+   TOOLCHAIN_VARIANT_COMPILER STREQUAL "default")
+ include(${ZEPHYR_BASE}/cmake/toolchain/host/gnu/target.cmake)
+elseif (TOOLCHAIN_VARIANT_COMPILER STREQUAL "llvm")
+  include(${ZEPHYR_BASE}/cmake/toolchain/host/llvm/target.cmake)
+else()
+  message(FATAL_ERROR "Unsupported TOOLCHAIN_VARIANT_COMPILER: ${TOOLCHAIN_VARIANT_COMPILER}")
+endif()
diff --git a/cmake/toolchain/xt-clang/generic.cmake b/cmake/toolchain/xt-clang/generic.cmake
index 66a56a2adb157..3dc86a15b8000 100644
--- a/cmake/toolchain/xt-clang/generic.cmake
+++ b/cmake/toolchain/xt-clang/generic.cmake
@@ -16,5 +16,6 @@ set(LINKER xt-ld)
 # obtain license information from remote licensing servers. So here
 # forces the assembler ID to be GNU to speed things up a bit.
 set(CMAKE_ASM_COMPILER_ID "GNU")
+set(TOOLCHAIN_HAS_LIBCXX ON CACHE BOOL "True if toolchain supports libc++")
 
 message(STATUS "Found toolchain: xt-clang (${XTENSA_TOOLCHAIN_PATH})")
diff --git a/cmake/toolchain/zephyr/generic.cmake b/cmake/toolchain/zephyr/generic.cmake
index f59d18c56fcd9..f051f3146bfd5 100644
--- a/cmake/toolchain/zephyr/generic.cmake
+++ b/cmake/toolchain/zephyr/generic.cmake
@@ -1,7 +1,25 @@
 # SPDX-License-Identifier: Apache-2.0
 
-include(${ZEPHYR_SDK_INSTALL_DIR}/cmake/zephyr/generic.cmake)
+if(TOOLCHAIN_VARIANT_COMPILER STREQUAL "gnu" OR
+    NOT DEFINED TOOLCHAIN_VARIANT_COMPILER)
+  if(EXISTS ${ZEPHYR_SDK_INSTALL_DIR}/cmake/zephyr/gnu/generic.cmake)
+    include(${ZEPHYR_SDK_INSTALL_DIR}/cmake/zephyr/gnu/generic.cmake)
+  else()
+    include(${ZEPHYR_SDK_INSTALL_DIR}/cmake/zephyr/generic.cmake)
+  endif()
+  set(TOOLCHAIN_VARIANT_COMPILER "gnu" CACHE STRING "compiler used by the toolchain variant" FORCE)
 
-set(TOOLCHAIN_KCONFIG_DIR ${ZEPHYR_SDK_INSTALL_DIR}/cmake/zephyr)
+  set(TOOLCHAIN_KCONFIG_DIR ${ZEPHYR_SDK_INSTALL_DIR}/cmake/zephyr)
+  # Zephyr SDK < 0.17.1 does not set TOOLCHAIN_HAS_GLIBCXX
+  set(TOOLCHAIN_HAS_GLIBCXX ON CACHE BOOL "True if toolchain supports libstdc++")
+  message(STATUS "Found toolchain: zephyr ${SDK_VERSION} (${ZEPHYR_SDK_INSTALL_DIR})")
+elseif(TOOLCHAIN_VARIANT_COMPILER STREQUAL "llvm")
+  include(${ZEPHYR_SDK_INSTALL_DIR}/cmake/zephyr/llvm/generic.cmake)
+  set(TOOLCHAIN_VARIANT_COMPILER "llvm" CACHE STRING "compiler used by the toolchain variant" FORCE)
 
-message(STATUS "Found toolchain: zephyr ${SDK_VERSION} (${ZEPHYR_SDK_INSTALL_DIR})")
+  set(TOOLCHAIN_KCONFIG_DIR ${ZEPHYR_SDK_INSTALL_DIR}/cmake/zephyr)
+
+  message(STATUS "Found toolchain: zephyr ${SDK_VERSION} (${ZEPHYR_SDK_INSTALL_DIR})")
+else()
+  message(FATAL_ERROR "Unsupported TOOLCHAIN_VARIANT_COMPILER: ${TOOLCHAIN_VARIANT_COMPILER}")
+endif()
diff --git a/cmake/toolchain/zephyr/target.cmake b/cmake/toolchain/zephyr/target.cmake
index 9eda6fa4e398e..b9cb47102390f 100644
--- a/cmake/toolchain/zephyr/target.cmake
+++ b/cmake/toolchain/zephyr/target.cmake
@@ -1,3 +1,16 @@
 # SPDX-License-Identifier: Apache-2.0
 
-include(${ZEPHYR_SDK_INSTALL_DIR}/cmake/zephyr/target.cmake)
+if(TOOLCHAIN_VARIANT_COMPILER STREQUAL "gnu" OR
+   TOOLCHAIN_VARIANT_COMPILER STREQUAL "default")
+  set(TOOLCHAIN_VARIANT_COMPILER gnu CACHE STRING "Variant compiler being used")
+  if(EXISTS ${ZEPHYR_SDK_INSTALL_DIR}/cmake/zephyr/gnu/target.cmake)
+    include(${ZEPHYR_SDK_INSTALL_DIR}/cmake/zephyr/gnu/target.cmake)
+  else()
+    include(${ZEPHYR_SDK_INSTALL_DIR}/cmake/zephyr/target.cmake)
+  endif()
+elseif (TOOLCHAIN_VARIANT_COMPILER STREQUAL "llvm")
+  set(TOOLCHAIN_VARIANT_COMPILER llvm CACHE STRING "Variant compiler being used")
+  include(${ZEPHYR_SDK_INSTALL_DIR}/cmake/zephyr/llvm/target.cmake)
+else()
+  message(FATAL_ERROR "Unsupported TOOLCHAIN_VARIANT_COMPILER: ${TOOLCHAIN_VARIANT_COMPILER}")
+endif()
diff --git a/cmake/verify-toolchain.cmake b/cmake/verify-toolchain.cmake
index 0c6f1771e512f..33d04a098878d 100644
--- a/cmake/verify-toolchain.cmake
+++ b/cmake/verify-toolchain.cmake
@@ -32,10 +32,12 @@ find_package(HostTools)
 if("${FORMAT}" STREQUAL "json")
   set(json "{\"ZEPHYR_TOOLCHAIN_VARIANT\" : \"${ZEPHYR_TOOLCHAIN_VARIANT}\", ")
   string(APPEND json "\"SDK_VERSION\": \"${SDK_VERSION}\", ")
+  string(APPEND json "\"TOOLCHAIN_VARIANT_COMPILER\": \"${TOOLCHAIN_VARIANT_COMPILER}\", ")
   string(APPEND json "\"ZEPHYR_SDK_INSTALL_DIR\" : \"${ZEPHYR_SDK_INSTALL_DIR}\"}")
   _message("${json}")
 else()
   message(STATUS "ZEPHYR_TOOLCHAIN_VARIANT: ${ZEPHYR_TOOLCHAIN_VARIANT}")
+  message(STATUS "TOOLCHAIN_VARIANT_COMPILER: ${TOOLCHAIN_VARIANT_COMPILER}")
   if(DEFINED SDK_VERSION)
     message(STATUS "SDK_VERSION: ${SDK_VERSION}")
   endif()
diff --git a/lib/cpp/CMakeLists.txt b/lib/cpp/CMakeLists.txt
index 3ac7701daaea5..ae05319914bf0 100644
--- a/lib/cpp/CMakeLists.txt
+++ b/lib/cpp/CMakeLists.txt
@@ -1,5 +1,13 @@
 # SPDX-License-Identifier: Apache-2.0
 
+if(CONFIG_LIBCXX_LIBCPP)
+  # LLVM C++ Standard Library makes use of POSIX and GNU C extension functions
+  # in its headers.
+  zephyr_compile_definitions($<$<COMPILE_LANGUAGE:CXX>:_POSIX_C_SOURCE=200809L>)
+  zephyr_compile_definitions($<$<COMPILE_LANGUAGE:CXX>:_XOPEN_SOURCE=700>)
+  zephyr_compile_definitions($<$<COMPILE_LANGUAGE:CXX>:_GNU_SOURCE>)
+endif()
+
 add_subdirectory(abi)
 
 add_subdirectory_ifdef(CONFIG_MINIMAL_LIBCPP minimal)
diff --git a/lib/cpp/Kconfig b/lib/cpp/Kconfig
index 6950743903331..b3465e039a6a1 100644
--- a/lib/cpp/Kconfig
+++ b/lib/cpp/Kconfig
@@ -101,7 +101,7 @@ config FULL_LIBCPP_SUPPORTED
 choice LIBCPP_IMPLEMENTATION
 	prompt "C++ Standard Library Implementation"
 	default EXTERNAL_LIBCPP if REQUIRES_FULL_LIBCPP && NATIVE_BUILD
-	default LIBCXX_LIBCPP if REQUIRES_FULL_LIBCPP && "$(ZEPHYR_TOOLCHAIN_VARIANT)" = "llvm"
+	default LIBCXX_LIBCPP if REQUIRES_FULL_LIBCPP && "$(TOOLCHAIN_HAS_LIBCXX)" = "y" && "$(TOOLCHAIN_VARIANT_COMPILER)" = "llvm"
 	default GLIBCXX_LIBCPP if REQUIRES_FULL_LIBCPP
 	default MINIMAL_LIBCPP
 
@@ -117,6 +117,7 @@ config MINIMAL_LIBCPP
 
 config GLIBCXX_LIBCPP
 	bool "GNU C++ Standard Library"
+	depends on "$(TOOLCHAIN_HAS_GLIBCXX)" = "y"
 	depends on NEWLIB_LIBC || PICOLIBC
 	select FULL_LIBCPP_SUPPORTED
 	help
@@ -125,8 +126,9 @@ config GLIBCXX_LIBCPP
 
 config LIBCXX_LIBCPP
 	bool "LLVM C++ Standard Library"
-	depends on NEWLIB_LIBC
-	depends on "$(ZEPHYR_TOOLCHAIN_VARIANT)" = "llvm"
+	depends on "$(TOOLCHAIN_HAS_LIBCXX)" = "y"
+	depends on NEWLIB_LIBC || PICOLIBC
+	depends on "$(TOOLCHAIN_VARIANT_COMPILER)" = "llvm"
 	select FULL_LIBCPP_SUPPORTED
 	help
 	  Build with LLVM C++ Standard Library (libc++) provided by LLVM
diff --git a/lib/runtime/Kconfig b/lib/runtime/Kconfig
index 9be8ac5b7aead..9c6ad2624781f 100644
--- a/lib/runtime/Kconfig
+++ b/lib/runtime/Kconfig
@@ -4,7 +4,7 @@
 config COMPILER_RT_SUPPORTED
 	bool
 	default y
-	depends on "$(ZEPHYR_TOOLCHAIN_VARIANT)" = "llvm"
+	depends on "$(TOOLCHAIN_VARIANT_COMPILER)" = "llvm"
 	help
 	  Selected when the compiler supports compiler-rt runtime library.
 
diff --git a/modules/trusted-firmware-m/CMakeLists.txt b/modules/trusted-firmware-m/CMakeLists.txt
index 5e066130b2627..b206ed9c3657b 100644
--- a/modules/trusted-firmware-m/CMakeLists.txt
+++ b/modules/trusted-firmware-m/CMakeLists.txt
@@ -224,7 +224,13 @@ if (CONFIG_BUILD_WITH_TFM)
   if(${ZEPHYR_TOOLCHAIN_VARIANT} STREQUAL "zephyr")
     set(TFM_TOOLCHAIN_FILE "toolchain_GNUARM.cmake")
     set(TFM_TOOLCHAIN_PREFIX "arm-zephyr-eabi")
-    set(TFM_TOOLCHAIN_PATH ${ZEPHYR_SDK_INSTALL_DIR}/arm-zephyr-eabi/bin)
+    if(${TOOLCHAIN_VARIANT_COMPILER} STREQUAL "gnu")
+      set(TFM_TOOLCHAIN_PATH ${ZEPHYR_SDK_INSTALL_DIR}/gnu/arm-zephyr-eabi/bin)
+    elseif(${TOOLCHAIN_VARIANT_COMPILER} STREQUAL "llvm")
+      set(TFM_TOOLCHAIN_PATH ${ZEPHYR_SDK_INSTALL_DIR}/llvm/bin)
+    else()
+      set(TFM_TOOLCHAIN_PATH ${ZEPHYR_SDK_INSTALL_DIR}/arm-zephyr-eabi/bin)
+    endif()
   elseif(${ZEPHYR_TOOLCHAIN_VARIANT} STREQUAL "gnuarmemb")
     set(TFM_TOOLCHAIN_FILE "toolchain_GNUARM.cmake")
     set(TFM_TOOLCHAIN_PREFIX "arm-none-eabi")
diff --git a/scripts/pylib/twister/twisterlib/environment.py b/scripts/pylib/twister/twisterlib/environment.py
index 47942ba1cd139..1fc79cd998d58 100644
--- a/scripts/pylib/twister/twisterlib/environment.py
+++ b/scripts/pylib/twister/twisterlib/environment.py
@@ -1198,5 +1198,7 @@ def get_toolchain(self):
         except Exception as e:
             print(str(e))
             sys.exit(2)
-        self.toolchain = json.loads(result['stdout'])['ZEPHYR_TOOLCHAIN_VARIANT']
-        logger.info(f"Using '{self.toolchain}' toolchain.")
+        _variant = json.loads(result['stdout'])['ZEPHYR_TOOLCHAIN_VARIANT']
+        self.compiler = json.loads(result['stdout'])['TOOLCHAIN_VARIANT_COMPILER']
+        self.toolchain = f"{_variant}/{self.compiler}"
+        logger.info(f"Using '{self.toolchain}' toolchain variant.")
diff --git a/scripts/pylib/twister/twisterlib/testinstance.py b/scripts/pylib/twister/twisterlib/testinstance.py
index 8b36c8e7f9686..33cae1c2a1b0e 100644
--- a/scripts/pylib/twister/twisterlib/testinstance.py
+++ b/scripts/pylib/twister/twisterlib/testinstance.py
@@ -74,7 +74,7 @@ def __init__(self, testsuite, platform, toolchain, outdir):
 
         if testsuite.detailed_test_id:
             self.build_dir = os.path.join(
-                outdir, platform.normalized_name, self.toolchain, testsuite.name
+                outdir, platform.normalized_name, self.toolchain.replace('/', '_'), testsuite.name
             )
         else:
             # if suite is not in zephyr,
diff --git a/scripts/pylib/twister/twisterlib/testplan.py b/scripts/pylib/twister/twisterlib/testplan.py
index 32dc7d8cef6db..fec01d34c240e 100755
--- a/scripts/pylib/twister/twisterlib/testplan.py
+++ b/scripts/pylib/twister/twisterlib/testplan.py
@@ -880,11 +880,10 @@ def apply_filters(self, **kwargs):
                 if itoolchain:
                     toolchain = itoolchain
                 elif plat.arch in ['posix', 'unit']:
-                    # workaround until toolchain variant in zephyr is overhauled and improved.
-                    if self.env.toolchain in ['llvm']:
-                        toolchain = 'llvm'
+                    if self.env.toolchain in ['host/llvm']:
+                        toolchain = 'host/llvm'
                     else:
-                        toolchain = 'host'
+                        toolchain = 'host/gnu'
                 else:
                     toolchain = "zephyr" if not self.env.toolchain else self.env.toolchain
 
@@ -998,7 +997,9 @@ def apply_filters(self, **kwargs):
                     instance.add_filter("Native platform requires Linux", Filters.ENVIRONMENT)
 
                 if not force_toolchain \
-                        and toolchain and (toolchain not in plat.supported_toolchains):
+                        and toolchain and (toolchain not in plat.supported_toolchains) and \
+                                        (toolchain.split('/')[0] not in plat.supported_toolchains):
+
                     instance.add_filter(
                         f"Not supported by the toolchain: {toolchain}",
                         Filters.PLATFORM
diff --git a/submanifests/optional.yaml b/submanifests/optional.yaml
index 04bdd669a921a..81985cbabc6b1 100644
--- a/submanifests/optional.yaml
+++ b/submanifests/optional.yaml
@@ -23,7 +23,7 @@ manifest:
       groups:
         - optional
     - name: psa-arch-tests
-      revision: 2cadb02a72eacda7042505dcbdd492371e8ce024
+      revision: pull/14/head
       path: modules/tee/tf-m/psa-arch-tests
       remote: upstream
       groups:
diff --git a/subsys/testsuite/Kconfig b/subsys/testsuite/Kconfig
index 9e72a5696fdb2..78620e7d806d0 100644
--- a/subsys/testsuite/Kconfig
+++ b/subsys/testsuite/Kconfig
@@ -56,7 +56,7 @@ config COVERAGE_NATIVE_GCOV
 config COVERAGE_NATIVE_SOURCE
 	bool "Host compiler source based code coverage"
 	depends on NATIVE_BUILD
-	depends on "$(ZEPHYR_TOOLCHAIN_VARIANT)" = "llvm"
+	depends on "$(TOOLCHAIN_VARIANT_COMPILER)" = "llvm"
 	help
 	  Build natively with the compiler source based coverage options.
 	  Today this is only supported with LLVM
diff --git a/tests/lib/c_lib/common/testcase.yaml b/tests/lib/c_lib/common/testcase.yaml
index 4d184b9536f5f..4fb1e73538ea8 100644
--- a/tests/lib/c_lib/common/testcase.yaml
+++ b/tests/lib/c_lib/common/testcase.yaml
@@ -2,6 +2,9 @@ common:
   tags:
     - clib
   ignore_faults: true
+  arch_exclude:
+    # see #89839
+    - rx
   integration_platforms:
     - mps2/an385
 tests:
diff --git a/tests/lib/c_lib/thrd/testcase.yaml b/tests/lib/c_lib/thrd/testcase.yaml
index e11360efd2eaf..ebc4099b4af4a 100644
--- a/tests/lib/c_lib/thrd/testcase.yaml
+++ b/tests/lib/c_lib/thrd/testcase.yaml
@@ -9,6 +9,11 @@ common:
   platform_key:
     - arch
     - simulation
+  filter: not CONFIG_NATIVE_APPLICATION
+  arch_exclude:
+    # see #89839
+    - rx
+  skip: true
 tests:
   libraries.libc.c11_threads.minimal:
     tags: minimal_libc
diff --git a/tests/lib/cpp/libcxx/testcase.yaml b/tests/lib/cpp/libcxx/testcase.yaml
index 566a0d689d3c1..333e649d89761 100644
--- a/tests/lib/cpp/libcxx/testcase.yaml
+++ b/tests/lib/cpp/libcxx/testcase.yaml
@@ -1,6 +1,11 @@
+common:
+  arch_exclude:
+    # see #89839
+    - rx
 tests:
+  # GNU C++ Standard Library (libstdc++)
   cpp.libcxx.glibcxx.newlib:
-    filter: TOOLCHAIN_HAS_NEWLIB == 1
+    filter: TOOLCHAIN_HAS_GLIBCXX == 1 and TOOLCHAIN_HAS_NEWLIB == 1
     toolchain_exclude: xcc
     min_flash: 54
     min_ram: 24
@@ -12,7 +17,7 @@ tests:
     integration_platforms:
       - mps2/an385
   cpp.libcxx.glibcxx.newlib_nano:
-    filter: TOOLCHAIN_HAS_NEWLIB == 1 and CONFIG_HAS_NEWLIB_LIBC_NANO
+    filter: TOOLCHAIN_HAS_GLIBCXX == 1 and TOOLCHAIN_HAS_NEWLIB == 1 and CONFIG_HAS_NEWLIB_LIBC_NANO
     toolchain_exclude: xcc
     min_flash: 54
     tags: cpp
@@ -24,7 +29,7 @@ tests:
     integration_platforms:
       - mps2/an385
   cpp.libcxx.glibcxx.picolibc:
-    filter: TOOLCHAIN_HAS_PICOLIBC == 1
+    filter: TOOLCHAIN_HAS_GLIBCXX == 1 and TOOLCHAIN_HAS_PICOLIBC == 1
     toolchain_exclude: xcc
     tags: cpp
     timeout: 60
@@ -34,6 +39,19 @@ tests:
       - CONFIG_CPP_EXCEPTIONS=y
     integration_platforms:
       - mps2/an385
+  # LLVM C++ Standard Library (libc++)
+  cpp.libcxx.libcxx.picolibc:
+    filter: TOOLCHAIN_HAS_LIBCXX == 1 and TOOLCHAIN_HAS_PICOLIBC == 1
+    toolchain_exclude: xcc
+    tags: cpp
+    timeout: 60
+    extra_configs:
+      - CONFIG_PICOLIBC=y
+      - CONFIG_LIBCXX_LIBCPP=y
+      - CONFIG_CPP_EXCEPTIONS=y
+    integration_platforms:
+      - mps2/an385
+  # ARC MWDT C++ Standard Library
   cpp.libcxx.arcmwdtlib:
     toolchain_allow: arcmwdt
     min_flash: 54
@@ -41,6 +59,7 @@ tests:
     extra_configs:
       - CONFIG_ARCMWDT_LIBC=y
       - CONFIG_ARCMWDT_LIBCPP=y
+  # Host C++ Standard Library
   cpp.libcxx.host:
     arch_allow: posix
     tags: cpp
diff --git a/west.yml b/west.yml
index 945fa7fed0b44..8e01da12c2a14 100644
--- a/west.yml
+++ b/west.yml
@@ -311,7 +311,7 @@ manifest:
       revision: b03edc8e6282a963cd312cd0b409eb5ce263ea75
       path: modules/lib/gui/lvgl
     - name: mbedtls
-      revision: 85440ef5fffa95d0e9971e9163719189cf34d979
+      revision: pull/73/head
       path: modules/crypto/mbedtls
       groups:
         - crypto
@@ -364,7 +364,7 @@ manifest:
       groups:
         - tee
     - name: trusted-firmware-m
-      revision: cc800268f79779fa674b7085ecf507eb95b83ff9
+      revision: pull/134/head
       path: modules/tee/tf-m/trusted-firmware-m
       groups:
         - tee