diff --git a/libstdc++/config/posix.mt b/libstdc++/config/posix.mt
new file mode 100644
index 00000000000..6afe1e514d9
--- /dev/null
+++ b/libstdc++/config/posix.mt
@@ -0,0 +1 @@
+MT_CFLAGS = -D_PTHREADS
diff --git a/libstdc++/config/sol2pth.mt b/libstdc++/config/sol2pth.mt
new file mode 100644
index 00000000000..6afe1e514d9
--- /dev/null
+++ b/libstdc++/config/sol2pth.mt
@@ -0,0 +1 @@
+MT_CFLAGS = -D_PTHREADS
diff --git a/libstdc++/config/sol2solth.mt b/libstdc++/config/sol2solth.mt
new file mode 100644
index 00000000000..f809d0ace86
--- /dev/null
+++ b/libstdc++/config/sol2solth.mt
@@ -0,0 +1 @@
+MT_CFLAGS = -D_SOLTHREADS