diff --git a/UPDATING b/UPDATING
--- a/UPDATING
+++ b/UPDATING
@@ -27,6 +27,11 @@
 	world, or to merely disable the most expensive debugging functionality
 	at runtime, run "ln -s 'abort:false,junk:false' /etc/malloc.conf".)
 
+20250727:
+	LLVM's debugging assertions are now disabled in main by default.
+	The WITH_LLVM_ASSERTIONS src.conf(5) knob should be used to
+	enable it when working on LLVM or requesting help with it.
+
 20250726:
 	amd64 kernel configurations must contain "options SMP".
 
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 July 14, 2025
+.Dd July 27, 2025
 .Dt SRC.CONF 5
 .Os
 .Sh NAME
@@ -940,8 +940,9 @@
 Do not build the LLD linker during the bootstrap phase of
 the build.
 To be able to build the system an alternate linker must be provided via XLD.
-.It Va WITHOUT_LLVM_ASSERTIONS
-Disable debugging assertions in LLVM.
+.It Va WITH_LLVM_ASSERTIONS
+Enable debugging assertions in LLVM.
+Use when working on or requesting help with LLVM components.
 .It Va WITHOUT_LLVM_BINUTILS
 Install ELF Tool Chain's binary utilities instead of LLVM's.
 This includes
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
@@ -123,7 +123,6 @@
     LEGACY_CONSOLE \
     LLD \
     LLD_BOOTSTRAP \
-    LLVM_ASSERTIONS \
     LLVM_BINUTILS \
     LLVM_COV \
     LLVM_CXXFILT \
@@ -210,6 +209,7 @@
     HESIOD \
     LOADER_VERBOSE \
     LOADER_VERIEXEC_PASS_MANIFEST \
+    LLVM_ASSERTIONS \
     LLVM_FULL_DEBUGINFO \
     MALLOC_PRODUCTION \
     OFED_EXTRA \
diff --git a/tools/build/options/WITH_LLVM_ASSERTIONS b/tools/build/options/WITH_LLVM_ASSERTIONS
--- a/tools/build/options/WITH_LLVM_ASSERTIONS
+++ b/tools/build/options/WITH_LLVM_ASSERTIONS
@@ -1 +1,2 @@
 Enable debugging assertions in LLVM.
+Use when working on or requesting help with LLVM components.