diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 9fddb1e9ee0..998ea63b8a4 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,5 +1,11 @@
 2018-09-03  Jonathan Wakely  <jwakely@redhat.com>
 
+	PR libstdc++/78179
+	* testsuite/26_numerics/headers/cmath/hypot-long-double.cc: New test
+	that runs the long double part of hypot.cc.
+	* testsuite/26_numerics/headers/cmath/hypot.cc: Disable long double
+	tests unless TEST_HYPOT_LONG_DOUBLE is defined.
+
 	* include/bits/stl_vector.h (vector::_Temporary_value::_M_ptr):
 	Return raw pointer not allocator's pointer type.
 	(vector::_Temporary_value::_M_val): Use _M_ptr.
diff --git a/libstdc++-v3/testsuite/26_numerics/headers/cmath/hypot-long-double.cc b/libstdc++-v3/testsuite/26_numerics/headers/cmath/hypot-long-double.cc
new file mode 100644
index 00000000000..8a054735ce9
--- /dev/null
+++ b/libstdc++-v3/testsuite/26_numerics/headers/cmath/hypot-long-double.cc
@@ -0,0 +1,25 @@
+// Copyright (C) 2016-2018 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++17" }
+// { dg-do run { target c++17 } }
+// { dg-xfail-run-if "PR 78179" { powerpc-ibm-aix* hppa-*-linux* nios2-*-* } }
+
+// Run the long double tests from hypot.cc separately, because they fail on a
+// number of targets. See PR libstdc++/78179 for details.
+#define TEST_HYPOT_LONG_DOUBLE
+#include "hypot.cc"
diff --git a/libstdc++-v3/testsuite/26_numerics/headers/cmath/hypot.cc b/libstdc++-v3/testsuite/26_numerics/headers/cmath/hypot.cc
index 69840c8117a..36c7553c5e8 100644
--- a/libstdc++-v3/testsuite/26_numerics/headers/cmath/hypot.cc
+++ b/libstdc++-v3/testsuite/26_numerics/headers/cmath/hypot.cc
@@ -17,7 +17,6 @@
 
 // { dg-options "-std=gnu++17" }
 // { dg-do run { target c++17 } }
-// { dg-xfail-run-if "AIX long double" { powerpc-ibm-aix* } }
 
 #include <cmath>
 #include <type_traits>
@@ -126,9 +125,13 @@ const long double toler3 = 1e-16l;
 void
 test01()
 {
+  // See hypot-long-double.cc for this macro
+#ifndef TEST_HYPOT_LONG_DOUBLE
   test(data1, toler1);
   test(data2, toler2);
+#else
   test(data3, toler3);
+#endif
 }
 
 int