Index: sys/conf/kern.post.mk
===================================================================
--- sys/conf/kern.post.mk
+++ sys/conf/kern.post.mk
@@ -329,13 +329,19 @@
 .depend: .PRECIOUS ${SRCS}
 
 _ILINKS= machine
+CFLAGS+= -fdebug-prefix-map=./machine=${SYSDIR}/${MACHINE}/include
 .if ${MACHINE} != ${MACHINE_CPUARCH} && ${MACHINE} != "arm64"
 _ILINKS+= ${MACHINE_CPUARCH}
+CFLAGS+= -fdebug-prefix-map=./${MACHINE_CPUARCH}=${SYSDIR}/${MACHINE_CPUARCH}/include
 .endif
 .if ${MACHINE_CPUARCH} == "i386" || ${MACHINE_CPUARCH} == "amd64"
 _ILINKS+= x86
+CFLAGS+= -fdebug-prefix-map=./x86=${SYSDIR}/x86/include
 .endif
 
+# Ensure that DWARF info contains a full path for auto-generated headers.
+CFLAGS+= -fdebug-prefix-map=.=${.OBJDIR}
+
 # Ensure that the link exists without depending on it when it exists.
 .for _link in ${_ILINKS}
 .if !exists(${.OBJDIR}/${_link})
Index: sys/conf/kmod.mk
===================================================================
--- sys/conf/kmod.mk
+++ sys/conf/kmod.mk
@@ -268,14 +268,20 @@
 .endif
 
 _ILINKS=machine
+CFLAGS+= -fdebug-prefix-map=./machine=${SYSDIR}/${MACHINE}/include
 .if ${MACHINE} != ${MACHINE_CPUARCH} && ${MACHINE} != "arm64"
 _ILINKS+=${MACHINE_CPUARCH}
+CFLAGS+= -fdebug-prefix-map=./${MACHINE_CPUARCH}=${SYSDIR}/${MACHINE_CPUARCH}/include
 .endif
 .if ${MACHINE_CPUARCH} == "i386" || ${MACHINE_CPUARCH} == "amd64"
 _ILINKS+=x86
+CFLAGS+= -fdebug-prefix-map=./x86=${SYSDIR}/x86/include
 .endif
 CLEANFILES+=${_ILINKS}
 
+# Ensure that DWARF info contains a full path for auto-generated headers.
+CFLAGS+= -fdebug-prefix-map=.=${.OBJDIR}
+
 all: ${PROG}
 
 beforedepend: ${_ILINKS}