diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 48f1464b2184..fe1643d69cc6 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,5 +1,18 @@
 2019-01-06  Jonathan Wakely  <jwakely@redhat.com>
 
+	PR libstdc++/87431
+	* include/std/variant (_Variant_storage<true, _Types...>::_M_valid):
+	Check is_trivially_copyable instead of is_scalar.
+	(variant::emplace<N, Args>(Args&&...)): If construction of the new
+	contained value can throw and its type is trivially copyable then
+	construct into a temporary variant and move from it, to provide the
+	strong exception safety guarantee.
+	(variant::emplace<N, U, Args>(initializer_list<U>, Args&&...)):
+	Likewise.
+	* testsuite/20_util/variant/87431.cc: New test.
+	* testsuite/20_util/variant/run.cc: Adjust test so that throwing
+	conversion causes valueless state.
+
 	PR libstdc++/88607
 	* testsuite/17_intro/headers/c++1998/charset.cc: New test.
 	* testsuite/17_intro/headers/c++2011/charset.cc: New test.
diff --git a/libstdc++-v3/include/std/variant b/libstdc++-v3/include/std/variant
index 6f2205c35072..83cf99e9ae00 100644
--- a/libstdc++-v3/include/std/variant
+++ b/libstdc++-v3/include/std/variant
@@ -439,7 +439,7 @@ namespace __variant
       constexpr bool
       _M_valid() const noexcept
       {
-	if constexpr ((is_scalar_v<_Types> && ...))
+	if constexpr ((is_trivially_copyable_v<_Types> && ...))
 	  return true;
 	return this->_M_index != __index_type(variant_npos);
       }
@@ -1185,6 +1185,23 @@ namespace __variant
 	{
 	  static_assert(_Np < sizeof...(_Types),
 			"The index should be in [0, number of alternatives)");
+
+	  using type = variant_alternative_t<_Np, variant>;
+	  // If constructing the value can throw but move assigning it can't,
+	  // construct in a temporary and then move assign from it. This gives
+	  // the strong exception safety guarantee, ensuring we never become
+	  // valueless.
+	  if constexpr (is_trivially_copyable_v<type>
+	      && !is_nothrow_constructible_v<type, _Args...>)
+	    {
+	      // If move assignment cannot throw then we can provide the
+	      // strong exception safety guarantee, and never become valueless.
+	      variant __tmp(in_place_index<_Np>,
+			    std::forward<_Args>(__args)...);
+	      *this = std::move(__tmp);
+	      return std::get<_Np>(*this);
+	    }
+
 	  this->~variant();
 	  __try
 	    {
@@ -1208,6 +1225,20 @@ namespace __variant
 	{
 	  static_assert(_Np < sizeof...(_Types),
 			"The index should be in [0, number of alternatives)");
+
+	  using type = variant_alternative_t<_Np, variant>;
+	  if constexpr (is_trivially_copyable_v<type>
+	      && !is_nothrow_constructible_v<type, initializer_list<_Up>,
+					     _Args...>)
+	    {
+	      // If move assignment cannot throw then we can provide the
+	      // strong exception safety guarantee, and never become valueless.
+	      variant __tmp(in_place_index<_Np>, __il,
+			    std::forward<_Args>(__args)...);
+	      *this = std::move(__tmp);
+	      return std::get<_Np>(*this);
+	    }
+
 	  this->~variant();
 	  __try
 	    {
diff --git a/libstdc++-v3/testsuite/20_util/variant/87431.cc b/libstdc++-v3/testsuite/20_util/variant/87431.cc
new file mode 100644
index 000000000000..8c5c4a781540
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/variant/87431.cc
@@ -0,0 +1,71 @@
+// Copyright (C) 2019 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 } }
+
+#include <variant>
+#include <testsuite_hooks.h>
+
+void
+test01()
+{
+  struct ThrowingConversion {
+    operator int() { throw 0; }
+  };
+
+  std::variant<float, char, int> v{'a'};
+  try
+  {
+    ThrowingConversion x;
+    v.emplace<2>(x);
+    VERIFY(false);
+  }
+  catch (int)
+  {
+    VERIFY( !v.valueless_by_exception() );
+    VERIFY( v.index() == 1 );
+    VERIFY( std::get<1>(v) == 'a' );
+  }
+}
+
+void
+test02()
+{
+  struct ThrowingConstructor {
+    ThrowingConstructor(std::initializer_list<int>, char) { throw 1; }
+  };
+
+  std::variant<float, char, ThrowingConstructor> v{'a'};
+  try
+  {
+    v.emplace<2>({1, 2, 3}, '4');
+    VERIFY(false);
+  }
+  catch (int)
+  {
+    VERIFY( !v.valueless_by_exception() );
+    VERIFY( v.index() == 1 );
+    VERIFY( std::get<1>(v) == 'a' );
+  }
+}
+
+int
+main()
+{
+  test01();
+}
diff --git a/libstdc++-v3/testsuite/20_util/variant/run.cc b/libstdc++-v3/testsuite/20_util/variant/run.cc
index 124759240f9a..c5ea7df37ece 100644
--- a/libstdc++-v3/testsuite/20_util/variant/run.cc
+++ b/libstdc++-v3/testsuite/20_util/variant/run.cc
@@ -354,7 +354,7 @@ void test_hash()
   {
     struct A
     {
-      operator int()
+      operator string()
       {
         throw nullptr;
       }
@@ -362,7 +362,7 @@ void test_hash()
     variant<int, string> v;
     try
       {
-        v.emplace<0>(A{});
+        v.emplace<1>(A{});
       }
     catch (nullptr_t)
       {