diff --git a/Makefile.inc1 b/Makefile.inc1
index 8785320bd8d3..97b5b7b23dde 100644
--- a/Makefile.inc1
+++ b/Makefile.inc1
@@ -318,6 +318,19 @@ LOCALBASE?=	/usr/local
 CROSS_COMPILER_PREFIX?=${CROSS_TOOLCHAIN_PREFIX}
 CROSS_BINUTILS_PREFIX?=${CROSS_TOOLCHAIN_PREFIX}
 .endif
+
+# If we do not have a bootstrap binutils (because the in-tree one does not
+# support the target architecture), provide a default cross-binutils prefix.
+# This allows aarch64 builds, for example, to automatically use the
+# aarch64-binutils port or package.
+.if !empty(BROKEN_OPTIONS:MBINUTILS_BOOTSTRAP) && \
+    !defined(CROSS_BINUTILS_PREFIX)
+CROSS_BINUTILS_PREFIX=/usr/local/${TARGET_ARCH}-freebsd/bin/
+.if !exists(${CROSS_BINUTILS_PREFIX})
+.error In-tree binutils does not support the ${TARGET_ARCH} architecture. Install the ${TARGET_ARCH}-binutils port or package or set CROSS_BINUTILS_PREFIX.
+.endif
+.endif
+
 XCOMPILERS=	CC CXX CPP
 .for COMPILER in ${XCOMPILERS}
 .if defined(CROSS_COMPILER_PREFIX)