diff --git a/boards/arm/cxd56xx/spresense/scripts/Make.defs b/boards/arm/cxd56xx/spresense/scripts/Make.defs
index 3fad02e669..6850d1dfa9 100644
--- a/boards/arm/cxd56xx/spresense/scripts/Make.defs
+++ b/boards/arm/cxd56xx/spresense/scripts/Make.defs
@@ -41,7 +41,6 @@ ifneq ($(CONFIG_DEBUG_NOOPT),y)
 endif
 
 ARCHCFLAGS += -mabi=aapcs
-ARCHCXXFLAGS += -std=c++11
 ARCHWARNINGS = -Wall -Wstrict-prototypes -Wshadow -Wundef
 ARCHWARNINGSXX = -Wall -Wshadow -Wundef
 ARCHPICFLAGS = -fpic -msingle-pic-base -mpic-register=r10
diff --git a/boards/arm/stm32l4/nucleo-l476rg/scripts/Make.defs b/boards/arm/stm32l4/nucleo-l476rg/scripts/Make.defs
index 53c645e368..fdc3cc271e 100644
--- a/boards/arm/stm32l4/nucleo-l476rg/scripts/Make.defs
+++ b/boards/arm/stm32l4/nucleo-l476rg/scripts/Make.defs
@@ -41,10 +41,6 @@ CXXPICFLAGS = $(ARCHPICFLAGS) $(CXXFLAGS)
 CPPFLAGS := $(ARCHINCLUDES) $(ARCHDEFINES) $(EXTRAFLAGS)
 AFLAGS := $(CFLAGS) -D__ASSEMBLY__
 
-ifeq ($(CONFIG_LIBCXX),y)
-  CXXFLAGS += -std=c++14
-endif
-
 NXFLATLDFLAGS1 = -r -d -warn-common
 NXFLATLDFLAGS2 = $(NXFLATLDFLAGS1) -T$(TOPDIR)/binfmt/libnxflat/gnu-nxflat-pcrel.ld -no-check-sections
 LDNXFLATFLAGS = -e main -s 2048
diff --git a/boards/risc-v/bl602/bl602evb/scripts/Make.defs b/boards/risc-v/bl602/bl602evb/scripts/Make.defs
index 147277752e..0cff2525e3 100644
--- a/boards/risc-v/bl602/bl602evb/scripts/Make.defs
+++ b/boards/risc-v/bl602/bl602evb/scripts/Make.defs
@@ -34,7 +34,7 @@ ifneq ($(CONFIG_DEBUG_NOOPT),y)
 endif
 
 ARCHCPUFLAGS += -mno-relax
-ARCHCXXFLAGS += -std=c++17 -pipe
+ARCHCXXFLAGS += -pipe
 ARCHWARNINGS = -Wall -Wstrict-prototypes -Wshadow -Wundef
 ARCHWARNINGSXX = -Wall -Wshadow -Wundef
 ARCHPICFLAGS = -fpic -msingle-pic-base -mpic-register=r10
diff --git a/boards/risc-v/esp32c3/esp32c3-devkit/scripts/Make.defs b/boards/risc-v/esp32c3/esp32c3-devkit/scripts/Make.defs
index 16453b4d73..eaa5000d32 100644
--- a/boards/risc-v/esp32c3/esp32c3-devkit/scripts/Make.defs
+++ b/boards/risc-v/esp32c3/esp32c3-devkit/scripts/Make.defs
@@ -38,7 +38,7 @@ ifneq ($(CONFIG_DEBUG_NOOPT),y)
 endif
 
 ARCHCFLAGS += -msmall-data-limit=0
-ARCHCXXFLAGS += -msmall-data-limit=0 -std=c++17
+ARCHCXXFLAGS += -msmall-data-limit=0
 ARCHWARNINGS = -Wall -Wstrict-prototypes -Wshadow -Wundef
 ARCHWARNINGSXX = -Wall -Wshadow -Wundef
 ARCHPICFLAGS = -fpic
diff --git a/boards/sim/sim/sim/scripts/Make.defs b/boards/sim/sim/sim/scripts/Make.defs
index d625a0a0e1..ef671f9b41 100644
--- a/boards/sim/sim/sim/scripts/Make.defs
+++ b/boards/sim/sim/sim/scripts/Make.defs
@@ -116,16 +116,6 @@ AFLAGS := $(CFLAGS) -D__ASSEMBLY__
 RUSTFLAGS := $(ARCHOPTIMIZATIONRUST)
 
 ifeq ($(CONFIG_LIBCXX),y)
-  # Why c++17?
-  #  * libcxx seems to require c++11.
-  #  * The compiler defaults varies:
-  #      clang/macOS (from xcode): 199711L
-  #      gcc/ubuntu:               201402L
-  #  * There is a precedent to use c++14.
-  #    (boards/arm/stm32l4/nucleo-l476rg/scripts/Make.defs)
-  #  * libs/libxx/libcxx/src/barrier.cpp depends on aligned new
-  CXXFLAGS += -std=c++17
-
   ifeq ($(CONFIG_HOST_MACOS),y)
     # macOS uses libc++abi
     CXXFLAGS += -DLIBCXX_BUILDING_LIBCXXABI
diff --git a/boards/xtensa/esp32/esp32-devkitc/scripts/Make.defs b/boards/xtensa/esp32/esp32-devkitc/scripts/Make.defs
index eca5164631..5d324576de 100644
--- a/boards/xtensa/esp32/esp32-devkitc/scripts/Make.defs
+++ b/boards/xtensa/esp32/esp32-devkitc/scripts/Make.defs
@@ -61,7 +61,6 @@ ifneq ($(CONFIG_DEBUG_NOOPT),y)
   ARCHOPTIMIZATION += $(MAXOPTIMIZATION) -fno-strict-aliasing
 endif
 
-ARCHCXXFLAGS += -std=c++17
 ARCHWARNINGS = -Wall -Wstrict-prototypes -Wshadow -Wundef
 ARCHWARNINGSXX = -Wall -Wshadow -Wundef
 ARCHPICFLAGS = -fpic
diff --git a/boards/xtensa/esp32/esp32-ethernet-kit/scripts/Make.defs b/boards/xtensa/esp32/esp32-ethernet-kit/scripts/Make.defs
index 244cc754a7..4e006e736d 100644
--- a/boards/xtensa/esp32/esp32-ethernet-kit/scripts/Make.defs
+++ b/boards/xtensa/esp32/esp32-ethernet-kit/scripts/Make.defs
@@ -61,7 +61,6 @@ ifneq ($(CONFIG_DEBUG_NOOPT),y)
   ARCHOPTIMIZATION += $(MAXOPTIMIZATION) -fno-strict-aliasing
 endif
 
-ARCHCXXFLAGS += -std=c++17
 ARCHWARNINGS = -Wall -Wstrict-prototypes -Wshadow -Wundef
 ARCHWARNINGSXX = -Wall -Wshadow -Wundef
 ARCHPICFLAGS = -fpic
diff --git a/boards/xtensa/esp32/esp32-wrover-kit/scripts/Make.defs b/boards/xtensa/esp32/esp32-wrover-kit/scripts/Make.defs
index 4433a30800..3e636aecc6 100644
--- a/boards/xtensa/esp32/esp32-wrover-kit/scripts/Make.defs
+++ b/boards/xtensa/esp32/esp32-wrover-kit/scripts/Make.defs
@@ -61,7 +61,6 @@ ifneq ($(CONFIG_DEBUG_NOOPT),y)
   ARCHOPTIMIZATION += $(MAXOPTIMIZATION) -fno-strict-aliasing
 endif
 
-ARCHCXXFLAGS += -std=c++17
 ARCHWARNINGS = -Wall -Wstrict-prototypes -Wshadow -Wundef
 ARCHWARNINGSXX = -Wall -Wshadow -Wundef
 ARCHPICFLAGS = -fpic
diff --git a/boards/xtensa/esp32/ttgo_lora_esp32/scripts/Make.defs b/boards/xtensa/esp32/ttgo_lora_esp32/scripts/Make.defs
index 6483c7b40c..7d19c00574 100644
--- a/boards/xtensa/esp32/ttgo_lora_esp32/scripts/Make.defs
+++ b/boards/xtensa/esp32/ttgo_lora_esp32/scripts/Make.defs
@@ -61,7 +61,6 @@ ifneq ($(CONFIG_DEBUG_NOOPT),y)
   ARCHOPTIMIZATION += $(MAXOPTIMIZATION) -fno-strict-aliasing
 endif
 
-ARCHCXXFLAGS += -std=c++17
 ARCHWARNINGS = -Wall -Wstrict-prototypes -Wshadow -Wundef
 ARCHWARNINGSXX = -Wall -Wshadow -Wundef
 ARCHPICFLAGS = -fpic
diff --git a/boards/xtensa/esp32s2/esp32s2-saola-1/scripts/Make.defs b/boards/xtensa/esp32s2/esp32s2-saola-1/scripts/Make.defs
index 4ade769cb7..13c08a47f3 100644
--- a/boards/xtensa/esp32s2/esp32s2-saola-1/scripts/Make.defs
+++ b/boards/xtensa/esp32s2/esp32s2-saola-1/scripts/Make.defs
@@ -42,7 +42,6 @@ ifneq ($(CONFIG_DEBUG_NOOPT),y)
   ARCHOPTIMIZATION += $(MAXOPTIMIZATION) -fno-strict-aliasing
 endif
 
-ARCHCXXFLAGS += -std=c++17
 ARCHWARNINGS = -Wall -Wstrict-prototypes -Wshadow -Wundef
 ARCHWARNINGSXX = -Wall -Wshadow -Wundef
 ARCHPICFLAGS = -fpic
diff --git a/boards/xtensa/esp32s3/esp32s3-devkit/scripts/Make.defs b/boards/xtensa/esp32s3/esp32s3-devkit/scripts/Make.defs
index 0e4fe1d403..b53941c826 100644
--- a/boards/xtensa/esp32s3/esp32s3-devkit/scripts/Make.defs
+++ b/boards/xtensa/esp32s3/esp32s3-devkit/scripts/Make.defs
@@ -32,7 +32,6 @@ ifneq ($(CONFIG_DEBUG_NOOPT),y)
   ARCHOPTIMIZATION += $(MAXOPTIMIZATION) -fno-strict-aliasing -fno-strength-reduce
 endif
 
-ARCHCXXFLAGS += -std=c++17
 ARCHWARNINGS = -Wall -Wstrict-prototypes -Wshadow -Wundef
 ARCHWARNINGSXX = -Wall -Wshadow -Wundef
 ARCHPICFLAGS = -fpic