diff --git a/configure.ac b/configure.ac
index ad31249528eb..3887db5c395e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -5217,19 +5217,23 @@ AC_SUBST(LD)
 
 dnl ===================================================================
 dnl Check whether the linker supports -debug:fastlink, which links debug
-dnl builds faster. MSVC link.exe does; lld-link currently does not and would
-dnl warn on every link, falling back to -debug:full. Probe the selected linker
-dnl rather than hardcoding "lld has no fastlink", so a future lld-link that
-dnl gains support starts using it automatically.
+dnl builds faster. link.exe offered it from VS 2017 to VS 2022 and dropped it
+dnl in the VS 2026 toolset; lld-link never had it. Both then warn on every
+dnl link and fall back to -debug:full, so probe the linker that will be used,
+dnl and only pass the flag when it takes it silently.
 dnl ===================================================================
 HAVE_LINK_DEBUG_FASTLINK=
 if test "$_os" = "WINNT"; then
     AC_MSG_CHECKING([whether the linker supports -debug:fastlink])
-    if test -z "$LLD_LINK"; then
-        dnl MSVC link.exe supports it natively
-        HAVE_LINK_DEBUG_FASTLINK=TRUE
-    elif "$LLD_LINK" -debug:fastlink conftest-nonexistent.obj 2>&1 | grep -iq "debug:fastlink.*debug:full"; then
-        dnl the fallback warning means fastlink is not supported
+    if test -n "$LLD_LINK"; then
+        fastlink_linker=$LLD_LINK
+    else
+        dnl PATH doesn't cover the MSVC tools yet; link.exe sits next to cl.exe
+        fastlink_linker=`win_short_path_for_make "$MSVC_HOST_PATH/link.exe"`
+    fi
+    dnl the link fails on the missing input file, and any mention of the flag in
+    dnl the output is a complaint about the flag itself: not being able to use it
+    if "$fastlink_linker" -debug:fastlink conftest-nonexistent.obj 2>&1 | grep -iq "debug:fastlink"; then
         HAVE_LINK_DEBUG_FASTLINK=
     else
         HAVE_LINK_DEBUG_FASTLINK=TRUE