diff --git a/Misc/NEWS b/Misc/NEWS
index 31c83bdb149..ea227a4088f 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -191,6 +191,11 @@ Tests
 Build
 -----
 
+- Issue #8625: Turn off optimization in --with-pydebug builds with gcc.
+  (Optimization was unintentionally turned on in gcc --with-pydebug builds in
+  2.7 beta1 as a result of the issue #1628484 fix, combined with autoconf's
+  strange choice of default CFLAGS produced by AC_PROG_CC for gcc.)
+
 - Issue #8509: Fix quoting in help strings and code snippets in configure.in.
 
 - Issue #3646: It is now easily possible to install a Python framework into
diff --git a/configure b/configure
index ed2da6176f7..4ab9e55b322 100755
--- a/configure
+++ b/configure
@@ -1,5 +1,5 @@
 #! /bin/sh
-# From configure.in Revision: 80647 .
+# From configure.in Revision: 80665 .
 # Guess values for system-dependent variables and create Makefiles.
 # Generated by GNU Autoconf 2.61 for python 2.7.
 #
@@ -4659,7 +4659,7 @@ then
 	    if test "$Py_DEBUG" = 'true' ; then
 		# Optimization messes up debuggers, so turn it off for
 		# debug builds.
-		OPT="-g -Wall $STRICT_PROTO"
+		OPT="-g -O0 -Wall $STRICT_PROTO"
 	    else
 		OPT="-g $WRAP -O3 -Wall $STRICT_PROTO"
 	    fi
diff --git a/configure.in b/configure.in
index 4def2d42b89..21496838c32 100644
--- a/configure.in
+++ b/configure.in
@@ -942,7 +942,7 @@ then
 	    if test "$Py_DEBUG" = 'true' ; then
 		# Optimization messes up debuggers, so turn it off for
 		# debug builds.
-		OPT="-g -Wall $STRICT_PROTO"
+		OPT="-g -O0 -Wall $STRICT_PROTO"
 	    else
 		OPT="-g $WRAP -O3 -Wall $STRICT_PROTO"
 	    fi