diff --git a/.github/workflows/scripts/qemu-6-tests.sh b/.github/workflows/scripts/qemu-6-tests.sh
index c261cbfca06..41c34511357 100755
--- a/.github/workflows/scripts/qemu-6-tests.sh
+++ b/.github/workflows/scripts/qemu-6-tests.sh
@@ -79,6 +79,7 @@ function do_builtin_build() {
 
   cd $HOME/linux-$fullver
   ./scripts/config --enable ZFS
+  ./scripts/config --enable ZFS_DEBUG
   yes "" | make oldconfig
   make -j `nproc`
   ) &> /var/tmp/builtin.txt || rc=$?
diff --git a/config/zfs-build.m4 b/config/zfs-build.m4
index 1e1485c4cf4..7aabad3868b 100644
--- a/config/zfs-build.m4
+++ b/config/zfs-build.m4
@@ -39,6 +39,18 @@ dnl # (If INVARIANTS is detected, we need to force DEBUG, or strange panics
 dnl # can ensue.)
 dnl #
 AC_DEFUN([ZFS_AC_DEBUG], [
+	dnl #
+	dnl # In the Linux kernel copy-builtin build, assertion/debug support
+	dnl # is selected by CONFIG_ZFS_DEBUG (Kconfig).
+	dnl #
+	AH_BOTTOM([
+#ifdef CONFIG_ZFS
+#undef ZFS_DEBUG
+#ifdef CONFIG_ZFS_DEBUG
+#define ZFS_DEBUG 1
+#endif
+#endif])
+
 	AC_MSG_CHECKING([whether assertion support will be enabled])
 	AC_ARG_ENABLE([debug],
 		[AS_HELP_STRING([--enable-debug],
diff --git a/copy-builtin b/copy-builtin
index 9a430bfb289..d412437f556 100755
--- a/copy-builtin
+++ b/copy-builtin
@@ -43,6 +43,17 @@ config ZFS
 
 	  To compile this file system support as a module, choose M here.
 
+	  If unsure, say N.
+
+config ZFS_DEBUG
+	bool "ZFS debugging"
+	depends on ZFS
+	help
+	  Enable ZFS debugging. This turns on all ASSERT() assertions,
+	  enables additional debug-only code paths, and promotes
+	  compiler warnings to errors. This should only be enabled for
+	  development or troubleshooting.
+
 	  If unsure, say N.
 EOF
 
diff --git a/module/Kbuild.in b/module/Kbuild.in
index ff2c96b85ae..fa4085c84b0 100644
--- a/module/Kbuild.in
+++ b/module/Kbuild.in
@@ -4,9 +4,11 @@
 
 ZFS_MODULE_CFLAGS += -std=gnu11 -Wno-declaration-after-statement
 ZFS_MODULE_CFLAGS += -Wmissing-prototypes
-ZFS_MODULE_CFLAGS += @KERNEL_DEBUG_CFLAGS@ @KERNEL_NO_FORMAT_ZERO_LENGTH@
+ZFS_MODULE_CFLAGS += @KERNEL_NO_FORMAT_ZERO_LENGTH@
 
 ifneq ($(KBUILD_EXTMOD),)
+ZFS_MODULE_CFLAGS += @KERNEL_DEBUG_CFLAGS@
+ZFS_MODULE_CPPFLAGS += @KERNEL_DEBUG_CPPFLAGS@
 zfs_include = @abs_top_srcdir@/include
 icp_include = @abs_srcdir@/icp/include
 zstd_include = @abs_srcdir@/zstd/include
@@ -16,6 +18,12 @@ ZFS_MODULE_CFLAGS += -I@abs_top_builddir@/include
 src = @abs_srcdir@
 obj = @abs_builddir@
 else
+ifeq ($(CONFIG_ZFS_DEBUG),y)
+ZFS_MODULE_CFLAGS += -Werror
+ZFS_MODULE_CPPFLAGS += -DDEBUG -UNDEBUG -DZFS_DEBUG
+else
+ZFS_MODULE_CPPFLAGS += -UDEBUG -DNDEBUG
+endif
 zfs_include = $(srctree)/include/zfs
 icp_include = $(src)/icp/include
 zstd_include = $(src)/zstd/include
@@ -28,7 +36,6 @@ ZFS_MODULE_CFLAGS += -I$(zfs_include)/os/linux/spl
 ZFS_MODULE_CFLAGS += -I$(zfs_include)/os/linux/zfs
 ZFS_MODULE_CFLAGS += -I$(zfs_include)
 ZFS_MODULE_CPPFLAGS += -D_KERNEL
-ZFS_MODULE_CPPFLAGS += @KERNEL_DEBUG_CPPFLAGS@
 
 # KASAN enables -Werror=frame-larger-than=1024, which
 # breaks oh so many parts of our build.