diff --git a/UPDATING b/UPDATING
--- a/UPDATING
+++ b/UPDATING
@@ -27,6 +27,16 @@
 	world, or to merely disable the most expensive debugging functionality
 	at runtime, run "ln -s 'abort:false,junk:false' /etc/malloc.conf".)
 
+20240729:
+	The build now defaults to WITHOUT_CLEAN - i.e., no automatic clean
+	is performed at the beginning of buildworld or buildkernel.  The
+	WITH_CLEAN src.conf(5) knob can be used to restore the previous
+	behaviour.
+
+	If you encounter incremental build issues, please report them to the
+	freebsd-current mailing list so that a special-case dependency can be
+	added, if necessary.
+
 20240712:
 	Support for armv6 has been disconnected and is being removed.
 
diff --git a/share/man/man5/src.conf.5 b/share/man/man5/src.conf.5
--- a/share/man/man5/src.conf.5
+++ b/share/man/man5/src.conf.5
@@ -1,5 +1,5 @@
 .\" DO NOT EDIT-- this file is @generated by tools/build/options/makeman.
-.Dd May 22, 2024
+.Dd July 29, 2024
 .Dt SRC.CONF 5
 .Os
 .Sh NAME
@@ -383,8 +383,8 @@
 .It Va WITHOUT_CLANG_FULL
 Avoid building the ARCMigrate, Rewriter and StaticAnalyzer components of
 the Clang C/C++ compiler.
-.It Va WITHOUT_CLEAN
-Do not clean before building world and/or kernel.
+.It Va WITH_CLEAN
+Clean before building world and/or kernel.
 .It Va WITHOUT_CPP
 Do not build
 .Xr cpp 1 .
diff --git a/share/mk/src.opts.mk b/share/mk/src.opts.mk
--- a/share/mk/src.opts.mk
+++ b/share/mk/src.opts.mk
@@ -80,7 +80,6 @@
     CDDL \
     CLANG \
     CLANG_BOOTSTRAP \
-    CLEAN \
     CPP \
     CROSS_COMPILER \
     CRYPT \
@@ -195,6 +194,7 @@
     BHYVE_SNAPSHOT \
     CLANG_EXTRAS \
     CLANG_FORMAT \
+    CLEAN \
     DIALOG \
     DETECT_TZ_CHANGES \
     DISK_IMAGE_TOOLS_BOOTSTRAP \
diff --git a/tools/build/options/WITH_CLEAN b/tools/build/options/WITH_CLEAN
new file mode 100644
--- /dev/null
+++ b/tools/build/options/WITH_CLEAN
@@ -0,0 +1 @@
+Clean before building world and/or kernel.