diff --git a/configure.in b/configure.in
index 24fdbd6093c5..ee3b8022654e 100644
--- a/configure.in
+++ b/configure.in
@@ -1962,8 +1962,16 @@ case "$target" in
             dnl For profile-guided optimization
             PROFILE_GEN_CFLAGS="-GL"
             PROFILE_GEN_LDFLAGS="-LTCG:PGINSTRUMENT"
-            PROFILE_USE_CFLAGS="-GL"
-            dnl XXX: should be -LTCG:PGOPTIMIZE, but that fails on libxul
+            dnl XXX: PGO builds can fail with warnings treated as errors,
+            dnl specifically "no profile data available" appears to be
+            dnl treated as an error sometimes. This might be a consequence
+            dnl of using WARNINGS_AS_ERRORS in some modules, combined
+            dnl with the linker doing most of the work in the whole-program
+            dnl optimization/PGO case. I think it's probably a compiler bug,
+            dnl but we work around it here.
+            PROFILE_USE_CFLAGS="-GL -wd4624 -wd4952"
+            dnl XXX: should be -LTCG:PGOPTIMIZE, but that fails on libxul.
+            dnl Probably also a compiler bug, but what can you do?
             PROFILE_USE_LDFLAGS="-LTCG:PGUPDATE"
             if test -n "$_USE_DYNAMICBASE"; then
                LDFLAGS="$LDFLAGS -DYNAMICBASE"