diff --git a/configure.in b/configure.in
index 26f0ef5ea9e4..1ffa1c63983b 100644
--- a/configure.in
+++ b/configure.in
@@ -2274,8 +2274,17 @@ ia64*-hpux*)
         dnl For profile-guided optimization
         PROFILE_GEN_CFLAGS="-GL"
         PROFILE_GEN_LDFLAGS="-LTCG:PGINSTRUMENT"
-        PROFILE_USE_CFLAGS="-GL"
-        PROFILE_USE_LDFLAGS="-LTCG:PGOPTIMIZE"
+        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"
         LDFLAGS="$LDFLAGS -DYNAMICBASE"
         dnl Minimum reqiurement of Gecko is VS2010 or later which supports
         dnl both SSSE3 and SSE4.1.
diff --git a/js/src/configure.in b/js/src/configure.in
index fc4041ef5489..39b9d0de43e0 100644
--- a/js/src/configure.in
+++ b/js/src/configure.in
@@ -1806,8 +1806,17 @@ ia64*-hpux*)
         dnl For profile-guided optimization
         PROFILE_GEN_CFLAGS="-GL"
         PROFILE_GEN_LDFLAGS="-LTCG:PGINSTRUMENT"
-        PROFILE_USE_CFLAGS="-GL"
-        PROFILE_USE_LDFLAGS="-LTCG:PGOPTIMIZE"
+        dnl XXX: PGO builds can fail with warnings treated as errors,
+        dnl specifically "no profile data available" appears to be
+        dnl treated as an error sometimes. This might be a consequence
+        dnl of using WARNINGS_AS_ERRORS in some modules, combined
+        dnl with the linker doing most of the work in the whole-program
+        dnl optimization/PGO case. I think it's probably a compiler bug,
+        dnl but we work around it here.
+        PROFILE_USE_CFLAGS="-GL -wd4624 -wd4952"
+        dnl XXX: should be -LTCG:PGOPTIMIZE, but that fails on libxul.
+        dnl Probably also a compiler bug, but what can you do?
+        PROFILE_USE_LDFLAGS="-LTCG:PGUPDATE"
         LDFLAGS="$LDFLAGS -DYNAMICBASE"
     fi
     AC_DEFINE(HAVE_SNPRINTF)