Index: head/share/mk/bsd.compiler.mk
===================================================================
--- head/share/mk/bsd.compiler.mk
+++ head/share/mk/bsd.compiler.mk
@@ -19,6 +19,8 @@
 # COMPILER_FEATURES will contain one or more of the following, based on
 # compiler support for that feature:
 #
+# - c++17:     supports full (or nearly full) C++17 programming environment.
+# - c++14:     supports full (or nearly full) C++14 programming environment.
 # - c++11:     supports full (or nearly full) C++11 programming environment.
 # - retpoline: supports the retpoline speculative execution vulnerability
 #              mitigation.
@@ -200,9 +202,17 @@
 .endif
 
 ${X_}COMPILER_FEATURES=
-.if ${${X_}COMPILER_TYPE} == "clang" || \
+.if (${${X_}COMPILER_TYPE} == "clang" && ${${X_}COMPILER_VERSION} >= 30300) || \
 	(${${X_}COMPILER_TYPE} == "gcc" && ${${X_}COMPILER_VERSION} >= 40800)
 ${X_}COMPILER_FEATURES+=	c++11
+.endif
+.if (${${X_}COMPILER_TYPE} == "clang" && ${${X_}COMPILER_VERSION} >= 30400) || \
+	(${${X_}COMPILER_TYPE} == "gcc" && ${${X_}COMPILER_VERSION} >= 50000)
+${X_}COMPILER_FEATURES+=	c++14
+.endif
+.if (${${X_}COMPILER_TYPE} == "clang" && ${${X_}COMPILER_VERSION} >= 50000) || \
+	(${${X_}COMPILER_TYPE} == "gcc" && ${${X_}COMPILER_VERSION} >= 70000)
+${X_}COMPILER_FEATURES+=	c++17
 .endif
 .if ${${X_}COMPILER_TYPE} == "clang" && ${${X_}COMPILER_VERSION} >= 60000
 ${X_}COMPILER_FEATURES+=	retpoline