diff --git a/master.cfg b/master.cfg
index 73d6b39..42d60b3 100644
--- a/master.cfg
+++ b/master.cfg
@@ -936,7 +936,15 @@ The parameters of the class are:
       be called to test GDB.  It needs to accept the same arguments as
       the TestGDB class above.  The default is to use TestGDB.
 
-    - extra_conf_flags: extra flags to be passed to "configure".
+    - extra_conf_flags: extra configure flags to be passed to
+      "configure".  Should be a list (i.e., []).  The default is None.
+      Do not pass CFLAGS/CXXFLAGS here; use the variables below for
+      that.
+
+    - extra_CFLAGS: extra CFLAGS to be passed to "configure".
+      Should be a list (i.e., []).  The default is None.
+
+    - extra_CXXFLAGS: extra CXXFLAGS to be passed to "configure".
       Should be a list (i.e., []).  The default is None.
 
     - enable_targets_all: set this to True to pass
@@ -968,6 +976,12 @@ The parameters of the class are:
     - system_debuginfo_location: Set this to the location of the
       debuginfo files in the system.  Default: "/usr/lib/debug"
 
+    - default_CFLAGS: The default CFLAGS options that are always
+      passed to configure.  These are joined with extra_CFLAGS.
+
+    - default_CXXFLAGS: The default CXXFLAGS options that are always
+      passed to configure.  These are joined with extra_CXXFLAGS.
+
     """
     ConfigureClass = ConfigureGDB
     CompileClass = CompileGDB
@@ -977,6 +991,8 @@ The parameters of the class are:
     # Set this to False to skip the test
     run_testsuite = True
 
+    extra_CFLAGS = None
+    extra_CXXFLAGS = None
     extra_conf_flags = None
     enable_targets_all = True
 
@@ -997,6 +1013,10 @@ The parameters of the class are:
     use_system_debuginfo = True
     system_debuginfo_location = "/usr/lib/debug"
 
+    # Default CFLAGS/CXXFLAGS that are always passed to "configure".
+    default_CFLAGS = "-D_GLIBCXX_DEBUG"
+    default_CXXFLAGS= "-D_GLIBCXX_DEBUG"
+
     def __init__ (self, architecture_triplet = [], initial_delay = None):
         factory.BuildFactory.__init__ (self)
 
@@ -1025,14 +1045,23 @@ The parameters of the class are:
         if not self.extra_conf_flags:
             self.extra_conf_flags = []
 
+        if not self.extra_CFLAGS:
+            self.extra_CFLAGS = []
+
+        if not self.extra_CXXFLAGS:
+            self.extra_CXXFLAGS = []
+
         if self.enable_targets_all:
             self.extra_conf_flags.append ('--enable-targets=all')
 
         if self.use_system_debuginfo:
             self.extra_conf_flags.append ('--with-separate-debug-dir=%s' % self.system_debuginfo_location)
 
-        self.addStep (self.ConfigureClass (self.extra_conf_flags + architecture_triplet,
-                                           haltOnFailure = True))
+        self.extra_conf_flags.append ("CFLAGS=%s" % default_CFLAGS + ' '.join (extra_CFLAGS))
+        self.extra_conf_flags.append ("CXXFLAGS=%s" % default_CXXFLAGS + ' '.join (extra_CXXFLAGS))
+        self.extra_conf_flags.append (architecture_triplet)
+
+        self.addStep (self.ConfigureClass (extra_conf_flags, haltOnFailure = True))
 
         if not self.extra_make_flags:
             self.extra_make_flags = []
@@ -1122,7 +1151,8 @@ class RunTestGDBPlain_c64t64 (BuildAndTestGDBFactory):
 class RunTestGDBPlain_c32t32 (BuildAndTestGDBFactory):
     """Compiling on 32-bit, testing on 32-bit."""
     def __init__ (self, **kwargs):
-        self.extra_conf_flags = [ r'CFLAGS=-m32', 'CXXFLAGS=-m32' ]
+        self.extra_CFLAGS = [ '-m32' ]
+        self.extra_CXXFLAGS = self.extra_CFLAGS
         self.extra_make_check_flags = [ r'RUNTESTFLAGS=--target_board unix/-m32' ]
         BuildAndTestGDBFactory.__init__ (self, **kwargs)
 
@@ -1147,7 +1177,8 @@ class RunTestGDBNativeGDBServer_c64t32 (BuildAndTestGDBFactory):
 class RunTestGDBNativeGDBServer_c32t32 (BuildAndTestGDBFactory):
     """Compiling on 32-bit, testing native-gdbserver on 32-bit."""
     def __init__ (self, **kwargs):
-        self.extra_conf_flags = [ 'CFLAGS=-m32', 'CXXFLAGS=-m32' ]
+        self.extra_CFLAGS = [ '-m32' ]
+        self.extra_CXXFLAGS = self.extra_CFLAGS
         self.extra_make_check_flags = [ 'RUNTESTFLAGS=--target_board native-gdbserver/-m32']
         BuildAndTestGDBFactory.__init__ (self, **kwargs)
 
@@ -1166,7 +1197,8 @@ class RunTestGDBNativeExtendedGDBServer_c64t32 (BuildAndTestGDBFactory):
 class RunTestGDBNativeExtendedGDBServer_c32t32 (BuildAndTestGDBFactory):
     """Compiling on 64-bit, testing native-extended-gdbserver on 32-bit."""
     def __init__ (self, **kwargs):
-        self.extra_conf_flags = [ 'CFLAGS=-m32', 'CXXFLAGS=-m32' ]
+        self.extra_CFLAGS = [ '-m32' ]
+        self.extra_CXXFLAGS = self.extra_CFLAGS
         self.extra_make_check_flags = [ r'RUNTESTFLAGS=--target_board native-extended-gdbserver/-m32' ]
         BuildAndTestGDBFactory.__init__ (self, **kwargs)
 
@@ -1180,7 +1212,8 @@ class RunTestGDBIndexBuild (BuildAndTestGDBFactory):
 class RunTestGDBIndexBuild_c32t32 (BuildAndTestGDBFactory):
     """Testing with the "cc-with-tweaks.sh" passing -i.  32-bit version"""
     def __init__ (self, **kwargs):
-        self.extra_conf_flags = [ 'CFLAGS=-m32', 'CXXFLAGS=-m32' ]
+        self.extra_CFLAGS = [ '-m32' ]
+        self.extra_CXXFLAGS = self.extra_CFLAGS
         self.extra_make_check_flags = [ util.Interpolate ('CC_FOR_TARGET=/bin/sh %(prop:builddir)s/binutils-gdb/gdb/contrib/cc-with-tweaks.sh -i gcc'),
                                         util.Interpolate ('CXX_FOR_TARGET=/bin/sh %(prop:builddir)s/binutils-gdb/gdb/contrib/cc-with-tweaks.sh -i g++'),
                                         'RUNTESTFLAGS=--target_board unix/-m32' ]