diff --git a/configure b/configure
index 895ecba659..4279767a91 100755
--- a/configure
+++ b/configure
@@ -11336,7 +11336,7 @@ echo "${ECHO_T}$ac_cv_c_compiler_gnu" >&6
 GCC=`test $ac_compiler_gnu = yes && echo yes`
 ac_test_CFLAGS=${CFLAGS+set}
 ac_save_CFLAGS=$CFLAGS
-CFLAGS="-g"
+CFLAGS="$CFLAGS -g"
 echo "$as_me:$LINENO: checking whether $CC accepts -g" >&5
 echo $ECHO_N "checking whether $CC accepts -g... $ECHO_C" >&6
 if test "${ac_cv_prog_cc_g+set}" = set; then
@@ -11726,7 +11726,7 @@ fi
         unset ac_cv_prog_cc_g
         ac_test_CFLAGS=${CFLAGS+set}
 ac_save_CFLAGS=$CFLAGS
-CFLAGS="-g"
+CFLAGS="$CFLAGS -g"
 echo "$as_me:$LINENO: checking whether $CC accepts -g" >&5
 echo $ECHO_N "checking whether $CC accepts -g... $ECHO_C" >&6
 if test "${ac_cv_prog_cc_g+set}" = set; then
@@ -12564,9 +12564,9 @@ if test "$ac_test_CXXFLAGS" = set; then
   CXXFLAGS=$ac_save_CXXFLAGS
 elif test $ac_cv_prog_cxx_g = yes; then
   if test "$GXX" = yes; then
-    CXXFLAGS="-g -O2"
+    CXXFLAGS="$CXXFLAGS -g -O2"
   else
-    CXXFLAGS="-g"
+    CXXFLAGS="$CXXFLAGS -g"
   fi
 else
   if test "$GXX" = yes; then
@@ -12804,9 +12804,9 @@ if test "$ac_test_CXXFLAGS" = set; then
   CXXFLAGS=$ac_save_CXXFLAGS
 elif test $ac_cv_prog_cxx_g = yes; then
   if test "$GXX" = yes; then
-    CXXFLAGS="-g -O2"
+    CXXFLAGS="$CXXFLAGS -g -O2"
   else
-    CXXFLAGS="-g"
+    CXXFLAGS="$CXXFLAGS -g"
   fi
 else
   if test "$GXX" = yes; then
@@ -42219,8 +42219,14 @@ fi;
 
     case "${BAKEFILE_HOST}" in
       *-*-darwin* )
-                        CFLAGS="$CFLAGS -fno-common"
-        CXXFLAGS="$CXXFLAGS -fno-common"
+                        if test "x$GCC" = "xyes"; then
+            CFLAGS="$CFLAGS -fno-common"
+            CXXFLAGS="$CXXFLAGS -fno-common"
+        fi
+        if test "x$XLCC" = "xyes"; then
+            CFLAGS="$CFLAGS -qnocommon"
+            CXXFLAGS="$CXXFLAGS -qnocommon"
+        fi
         ;;
 
       *-pc-os2_emx | *-pc-os2-emx )
@@ -42583,7 +42589,12 @@ EOF
             SHARED_LD_MODULE_CXX="\${CXX} -bundle -single_module -headerpad_max_install_names -o"
         fi
 
-        PIC_FLAG="-dynamic -fPIC"
+        if test "x$GCC" == "xyes"; then
+            PIC_FLAG="-dynamic -fPIC"
+        fi
+        if test "x$XLCC" = "xyes"; then
+            PIC_FLAG="-dynamic -DPIC"
+        fi
       ;;
 
       *-*-aix* )