diff --git a/gcc/cp/call.c b/gcc/cp/call.c
index 9f03534c20c..aafc7acca24 100644
--- a/gcc/cp/call.c
+++ b/gcc/cp/call.c
@@ -4629,7 +4629,7 @@ perform_overload_resolution (tree fn,
    functions.  */
 
 static void
-print_error_for_call_failure (tree fn, vec<tree, va_gc> *args,
+print_error_for_call_failure (tree fn, const vec<tree, va_gc> *args,
 			      struct z_candidate *candidates)
 {
   tree targs = NULL_TREE;
@@ -4654,6 +4654,40 @@ print_error_for_call_failure (tree fn, vec<tree, va_gc> *args,
     print_z_candidates (loc, candidates);
 }
 
+/* Perform overload resolution on the set of deduction guides DGUIDES
+   using ARGS.  Returns the selected deduction guide, or error_mark_node
+   if overload resolution fails.  */
+
+tree
+perform_dguide_overload_resolution (tree dguides, const vec<tree, va_gc> *args,
+				    tsubst_flags_t complain)
+{
+  z_candidate *candidates;
+  bool any_viable_p;
+  tree result;
+
+  gcc_assert (deduction_guide_p (OVL_FIRST (dguides)));
+
+  /* Get the high-water mark for the CONVERSION_OBSTACK.  */
+  void *p = conversion_obstack_alloc (0);
+
+  z_candidate *cand = perform_overload_resolution (dguides, args, &candidates,
+						   &any_viable_p, complain);
+  if (!cand)
+    {
+      if (complain & tf_error)
+	print_error_for_call_failure (dguides, args, candidates);
+      result = error_mark_node;
+    }
+  else
+    result = cand->fn;
+
+  /* Free all the conversions we allocated.  */
+  obstack_free (&conversion_obstack, p);
+
+  return result;
+}
+
 /* Return an expression for a call to FN (a namespace-scope function,
    or a static member function) with the ARGS.  This may change
    ARGS.  */
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 36f99ccf189..6f713719589 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -6437,6 +6437,8 @@ extern void complain_about_bad_argument	(location_t arg_loc,
 						 tree from_type, tree to_type,
 						 tree fndecl, int parmnum);
 extern void maybe_inform_about_fndecl_for_bogus_argument_init (tree, int);
+extern tree perform_dguide_overload_resolution	(tree, const vec<tree, va_gc> *,
+						 tsubst_flags_t);
 
 
 /* A class for recording information about access failures (e.g. private
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 15947b2c812..732fb405adf 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -29382,7 +29382,7 @@ do_class_deduction (tree ptype, tree tmpl, tree init,
     if (tree guide = maybe_aggr_guide (tmpl, init, args))
       cands = lookup_add (guide, cands);
 
-  tree call = error_mark_node;
+  tree fndecl = error_mark_node;
 
   /* If this is list-initialization and the class has a list constructor, first
      try deducing from the list as a single argument, as [over.match.list].  */
@@ -29396,11 +29396,9 @@ do_class_deduction (tree ptype, tree tmpl, tree init,
       }
   if (list_cands)
     {
-      ++cp_unevaluated_operand;
-      call = build_new_function_call (list_cands, &args, tf_decltype);
-      --cp_unevaluated_operand;
+      fndecl = perform_dguide_overload_resolution (list_cands, args, tf_none);
 
-      if (call == error_mark_node)
+      if (fndecl == error_mark_node)
 	{
 	  /* That didn't work, now try treating the list as a sequence of
 	     arguments.  */
@@ -29416,31 +29414,22 @@ do_class_deduction (tree ptype, tree tmpl, tree init,
 	     "user-declared constructors", type);
       return error_mark_node;
     }
-  else if (!cands && call == error_mark_node)
+  else if (!cands && fndecl == error_mark_node)
     {
       error ("cannot deduce template arguments of %qT, as it has no viable "
 	     "deduction guides", type);
       return error_mark_node;
     }
 
-  if (call == error_mark_node)
-    {
-      ++cp_unevaluated_operand;
-      call = build_new_function_call (cands, &args, tf_decltype);
-      --cp_unevaluated_operand;
-    }
+  if (fndecl == error_mark_node)
+    fndecl = perform_dguide_overload_resolution (cands, args, tf_none);
 
-  if (call == error_mark_node)
+  if (fndecl == error_mark_node)
     {
       if (complain & tf_warning_or_error)
 	{
 	  error ("class template argument deduction failed:");
-
-	  ++cp_unevaluated_operand;
-	  call = build_new_function_call (cands, &args,
-					  complain | tf_decltype);
-	  --cp_unevaluated_operand;
-
+	  perform_dguide_overload_resolution (cands, args, complain);
 	  if (elided)
 	    inform (input_location, "explicit deduction guides not considered "
 		    "for copy-initialization");
@@ -29451,8 +29440,7 @@ do_class_deduction (tree ptype, tree tmpl, tree init,
      constructor is chosen, the initialization is ill-formed.  */
   else if (flags & LOOKUP_ONLYCONVERTING)
     {
-      tree fndecl = cp_get_callee_fndecl_nofold (call);
-      if (fndecl && DECL_NONCONVERTING_P (fndecl))
+      if (DECL_NONCONVERTING_P (fndecl))
 	{
 	  if (complain & tf_warning_or_error)
 	    {
@@ -29470,12 +29458,10 @@ do_class_deduction (tree ptype, tree tmpl, tree init,
 
   /* If CTAD succeeded but the type doesn't have any explicit deduction
      guides, this deduction might not be what the user intended.  */
-  if (call != error_mark_node && !any_dguides_p)
+  if (fndecl != error_mark_node && !any_dguides_p)
     {
-      tree fndecl = cp_get_callee_fndecl_nofold (call);
-      if (fndecl != NULL_TREE
-	  && (!DECL_IN_SYSTEM_HEADER (fndecl)
-	      || global_dc->dc_warn_system_headers)
+      if ((!DECL_IN_SYSTEM_HEADER (fndecl)
+	   || global_dc->dc_warn_system_headers)
 	  && warning (OPT_Wctad_maybe_unsupported,
 		      "%qT may not intend to support class template argument "
 		      "deduction", type))
@@ -29483,7 +29469,8 @@ do_class_deduction (tree ptype, tree tmpl, tree init,
 		"warning");
     }
 
-  return cp_build_qualified_type (TREE_TYPE (call), cp_type_quals (ptype));
+  return cp_build_qualified_type (TREE_TYPE (TREE_TYPE (fndecl)),
+				  cp_type_quals (ptype));
 }
 
 /* Replace occurrences of 'auto' in TYPE with the appropriate type deduced
diff --git a/gcc/testsuite/g++.dg/cpp1z/class-deduction88.C b/gcc/testsuite/g++.dg/cpp1z/class-deduction88.C
new file mode 100644
index 00000000000..f8fea966696
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/class-deduction88.C
@@ -0,0 +1,20 @@
+// PR c++/86439
+// { dg-do compile { target c++17 } }
+
+struct NC {
+  NC() = default;
+  NC(NC const&) = delete;
+  NC& operator=(NC const&) = delete;
+};
+
+template <int>
+struct C {
+  C(NC const&);
+};
+
+C(NC) -> C<0>;
+
+int main() {
+  NC nc;
+  C c(nc);
+}
diff --git a/gcc/testsuite/g++.dg/cpp1z/class-deduction89.C b/gcc/testsuite/g++.dg/cpp1z/class-deduction89.C
new file mode 100644
index 00000000000..dd898573022
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/class-deduction89.C
@@ -0,0 +1,15 @@
+// PR c++/86439
+// { dg-do compile { target c++17 } }
+
+struct B { };
+struct C { };
+
+template<class T>
+struct A {
+  A(T, B);
+};
+
+template<class T>
+A(T, C) -> A<T>;
+
+A a(0, {});
diff --git a/gcc/testsuite/g++.dg/cpp1z/class-deduction90.C b/gcc/testsuite/g++.dg/cpp1z/class-deduction90.C
new file mode 100644
index 00000000000..8b93193c7b0
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/class-deduction90.C
@@ -0,0 +1,16 @@
+// PR c++/86439
+// { dg-do compile { target c++17 } }
+
+struct less { };
+struct allocator { };
+
+template<class T, class U = less, class V = allocator>
+struct A {
+  A(T, U);
+  A(T, V);
+};
+
+template<class T, class U = less>
+A(T, U) -> A<T>;
+
+A a(0, {}); // { dg-error "ambiguous" }
diff --git a/libstdc++-v3/testsuite/23_containers/map/cons/deduction.cc b/libstdc++-v3/testsuite/23_containers/map/cons/deduction.cc
index e9628c4ac32..8def11ed574 100644
--- a/libstdc++-v3/testsuite/23_containers/map/cons/deduction.cc
+++ b/libstdc++-v3/testsuite/23_containers/map/cons/deduction.cc
@@ -39,10 +39,6 @@ static_assert(std::is_same_v<
 	      std::map<int, double>>);
 */
 
-static_assert(std::is_same_v<
-	      decltype(std::map{{std::pair{1, 2.0}, {2, 3.0}, {3, 4.0}}, {}}),
-	      std::map<int, double>>);
-
 /* This is not deducible, ambiguous candidates:
  * map(initializer_list<value_type>, const Compare&, const _Allocator& = {})
  * map(initializer_list<value_type>, const _Allocator&)
@@ -90,11 +86,6 @@ void f()
 				  std::less<int>{}, {}}),
 		std::map<int, double>>);
 
-  static_assert(std::is_same_v<
-		decltype(std::map(x.begin(), x.end(),
-				  {})),
-		std::map<int, double>>);
-
   static_assert(std::is_same_v<
 		decltype(std::map{x.begin(), x.end(),
 				  std::allocator<value_type>{}}),
@@ -143,11 +134,6 @@ void g()
 				  std::less<int>{}, {}}),
 		std::map<int, double>>);
 
-  static_assert(std::is_same_v<
-		decltype(std::map(x.begin(), x.end(),
-				  {})),
-		std::map<int, double>>);
-
   static_assert(std::is_same_v<
 		decltype(std::map{x.begin(), x.end(),
 				  std::allocator<value_type>{}}),
@@ -193,11 +179,6 @@ void h()
 				  std::less<int>{}, {}}),
 		std::map<int, double>>);
 
-  static_assert(std::is_same_v<
-		decltype(std::map(x.begin(), x.end(),
-				  {})),
-		std::map<int, double>>);
-
   static_assert(std::is_same_v<
 		decltype(std::map{x.begin(), x.end(),
 				  std::allocator<value_type>{}}),
diff --git a/libstdc++-v3/testsuite/23_containers/multimap/cons/deduction.cc b/libstdc++-v3/testsuite/23_containers/multimap/cons/deduction.cc
index 791cc963479..ff855081ab3 100644
--- a/libstdc++-v3/testsuite/23_containers/multimap/cons/deduction.cc
+++ b/libstdc++-v3/testsuite/23_containers/multimap/cons/deduction.cc
@@ -40,11 +40,6 @@ static_assert(std::is_same_v<
 	      std::multimap<int, double>>);
 */
 
-static_assert(std::is_same_v<
-	      decltype(std::multimap{{std::pair{1, 2.0}, {2, 3.0}, {3, 4.0}},
-		    {}}),
-	      std::multimap<int, double>>);
-
 static_assert(std::is_same_v<
 	      decltype(std::multimap{{value_type{1, 2.0}, {2, 3.0}, {3, 4.0}},
 				     {}, SimpleAllocator<value_type>{}}),
@@ -75,11 +70,6 @@ void f()
 				       std::less<int>{}, {}}),
 		std::multimap<int, double>>);
 
-  static_assert(std::is_same_v<
-		decltype(std::multimap(x.begin(), x.end(),
-				       {})),
-		std::multimap<int, double>>);
-
   static_assert(std::is_same_v<
 		decltype(std::multimap{x.begin(), x.end(),
 		      {},
@@ -117,11 +107,6 @@ void g()
 				       std::less<int>{}, {}}),
 		std::multimap<int, double>>);
 
-  static_assert(std::is_same_v<
-		decltype(std::multimap(x.begin(), x.end(),
-				       {})),
-		std::multimap<int, double>>);
-
   static_assert(std::is_same_v<
 		decltype(std::multimap{x.begin(), x.end(),
 				       {},
@@ -156,11 +141,6 @@ void h()
 				       std::less<int>{}, {}}),
 		std::multimap<int, double>>);
 
-  static_assert(std::is_same_v<
-		decltype(std::multimap(x.begin(), x.end(),
-				       {})),
-		std::multimap<int, double>>);
-
   static_assert(std::is_same_v<
 		decltype(std::multimap{x.begin(), x.end(),
 				       {},
diff --git a/libstdc++-v3/testsuite/23_containers/multiset/cons/deduction.cc b/libstdc++-v3/testsuite/23_containers/multiset/cons/deduction.cc
index ad12755ccc6..be7ca237e78 100644
--- a/libstdc++-v3/testsuite/23_containers/multiset/cons/deduction.cc
+++ b/libstdc++-v3/testsuite/23_containers/multiset/cons/deduction.cc
@@ -19,10 +19,6 @@ static_assert(std::is_same_v<
 	      decltype(std::multiset{{1, 2, 3}, std::less<int>{}, {}}),
 	      std::multiset<int>>);
 
-static_assert(std::is_same_v<
-	      decltype(std::multiset{{1, 2, 3}, {}}),
-	      std::multiset<int>>);
-
 static_assert(std::is_same_v<
 	      decltype(std::multiset{{1, 2, 3}, SimpleAllocator<int>{}}),
 	      std::multiset<int, std::less<int>, SimpleAllocator<int>>>);
@@ -50,11 +46,6 @@ void f()
 		      std::less<int>{}, {}}),
 		std::multiset<int>>);
 
-  static_assert(std::is_same_v<
-		decltype(std::multiset(x.begin(), x.end(),
-				  {})),
-		std::multiset<int>>);
-
   static_assert(std::is_same_v<
 		decltype(std::multiset{x.begin(), x.end(),
 				       std::allocator<int>{}}),
@@ -101,11 +92,6 @@ void g()
 				  std::less<int>{}, {}}),
 		std::multiset<int>>);
 
-  static_assert(std::is_same_v<
-		decltype(std::multiset(x.begin(), x.end(),
-				  {})),
-		std::multiset<int>>);
-
   static_assert(std::is_same_v<
 		decltype(std::multiset{x.begin(), x.end(),
 				  std::allocator<value_type>{}}),
diff --git a/libstdc++-v3/testsuite/23_containers/set/cons/deduction.cc b/libstdc++-v3/testsuite/23_containers/set/cons/deduction.cc
index 89a2c43b937..48d1a3ebbe2 100644
--- a/libstdc++-v3/testsuite/23_containers/set/cons/deduction.cc
+++ b/libstdc++-v3/testsuite/23_containers/set/cons/deduction.cc
@@ -20,11 +20,6 @@ static_assert(std::is_same_v<
 		    std::less<int>{}, {}}),
 	      std::set<int>>);
 
-static_assert(std::is_same_v<
-	      decltype(std::set{{1, 2, 3},
-		    {}}),
-	      std::set<int>>);
-
 static_assert(std::is_same_v<
 	      decltype(std::set{{1, 2, 3},
 		    SimpleAllocator<int>{}}),
@@ -56,11 +51,6 @@ void f()
 		      std::less<int>{}, {}}),
 		std::set<int>>);
 
-  static_assert(std::is_same_v<
-		decltype(std::set(x.begin(), x.end(),
-				  {})),
-		std::set<int>>);
-
   static_assert(std::is_same_v<
 		decltype(std::set{x.begin(), x.end(),
 		      {},
@@ -102,11 +92,6 @@ void g()
 				  std::less<int>{}, {}}),
 		std::set<int>>);
 
-  static_assert(std::is_same_v<
-		decltype(std::set(x.begin(), x.end(),
-				  {})),
-		std::set<int>>);
-
   static_assert(std::is_same_v<
 		decltype(std::set{x.begin(), x.end(),
 				  std::allocator<value_type>{}}),
diff --git a/libstdc++-v3/testsuite/23_containers/unordered_map/cons/deduction.cc b/libstdc++-v3/testsuite/23_containers/unordered_map/cons/deduction.cc
index d8489b23f8a..bd266492b2a 100644
--- a/libstdc++-v3/testsuite/23_containers/unordered_map/cons/deduction.cc
+++ b/libstdc++-v3/testsuite/23_containers/unordered_map/cons/deduction.cc
@@ -21,12 +21,6 @@ static_assert(std::is_same_v<
 		1}),
 	      std::unordered_map<int, double>>);
 
-static_assert(std::is_same_v<
-	      decltype(std::unordered_map{{std::pair{1, 2.0},
-		      {2, 3.0}, {3, 4.0}},
-		    {}, std::hash<int>{}, {}}),
-	      std::unordered_map<int, double>>);
-
 static_assert(std::is_same_v<
 	      decltype(std::unordered_map{{std::pair{1, 2.0},
 		      {2, 3.0}, {3, 4.0}},
@@ -57,16 +51,6 @@ void f()
 		      std::allocator<std::pair<const int, double>>{}}),
 		std::unordered_map<int, double>>);
 
-  static_assert(std::is_same_v<
-		decltype(std::unordered_map{x.begin(), x.end(),
-		      {}, std::hash<int>{}, {}}),
-		std::unordered_map<int, double>>);
-  
-  static_assert(std::is_same_v<
-		decltype(std::unordered_map(x.begin(), x.end(),
-		      {})),
-		std::unordered_map<int, double>>);
-
   static_assert(std::is_same_v<
 		decltype(std::unordered_map{x.begin(), x.end(), 1}),
 		std::unordered_map<int, double>>);
diff --git a/libstdc++-v3/testsuite/23_containers/unordered_multimap/cons/deduction.cc b/libstdc++-v3/testsuite/23_containers/unordered_multimap/cons/deduction.cc
index 13f54d43451..74a0165574d 100644
--- a/libstdc++-v3/testsuite/23_containers/unordered_multimap/cons/deduction.cc
+++ b/libstdc++-v3/testsuite/23_containers/unordered_multimap/cons/deduction.cc
@@ -15,12 +15,6 @@ static_assert(std::is_same_v<
 		      {2, 3.0}, {3, 4.0}}}),
 	      std::unordered_multimap<int, double>>);
 
-static_assert(std::is_same_v<
-	      decltype(std::unordered_multimap{{std::pair{1, 2.0},
-		      {2, 3.0}, {3, 4.0}},
-		    {}, std::hash<int>{}, {}}),
-	      std::unordered_multimap<int, double>>);
-
 static_assert(std::is_same_v<
 	      decltype(std::unordered_multimap{{std::pair{1, 2.0},
 		      {2, 3.0}, {3, 4.0}},
@@ -66,16 +60,6 @@ void f()
 		      std::allocator<std::pair<const int, double>>{}}),
 		std::unordered_multimap<int, double>>);
 
-  static_assert(std::is_same_v<
-		decltype(std::unordered_multimap{x.begin(), x.end(),
-		      {}, std::hash<int>{}, {}}),
-		std::unordered_multimap<int, double>>);
-  
-  static_assert(std::is_same_v<
-		decltype(std::unordered_multimap(x.begin(), x.end(),
-				  {})),
-		std::unordered_multimap<int, double>>);
-
   static_assert(std::is_same_v<
 		decltype(std::unordered_multimap(x.begin(), x.end(), 1)),
 		std::unordered_multimap<int, double>>);
diff --git a/libstdc++-v3/testsuite/23_containers/unordered_multiset/cons/deduction.cc b/libstdc++-v3/testsuite/23_containers/unordered_multiset/cons/deduction.cc
index 1850237e44c..e3006fdbfe3 100644
--- a/libstdc++-v3/testsuite/23_containers/unordered_multiset/cons/deduction.cc
+++ b/libstdc++-v3/testsuite/23_containers/unordered_multiset/cons/deduction.cc
@@ -9,11 +9,6 @@ static_assert(std::is_same_v<
 	      decltype(std::unordered_multiset{1, 2, 3}),
 	      std::unordered_multiset<int>>);
 
-static_assert(std::is_same_v<
-	      decltype(std::unordered_multiset{{1, 2, 3},
-		    0, std::hash<int>{}, {}}),
-	      std::unordered_multiset<int>>);
-
 static_assert(std::is_same_v<
 	      decltype(std::unordered_multiset{{1, 2, 3},
 		    {}}),
@@ -76,11 +71,6 @@ void f()
 		      std::allocator<int>{}}),
 		std::unordered_multiset<int>>);
 
-  static_assert(std::is_same_v<
-		decltype(std::unordered_multiset{x.begin(), x.end(),
-		      {}, std::hash<int>{}, {}}),
-		std::unordered_multiset<int>>);
-
   static_assert(std::is_same_v<
 		decltype(std::unordered_multiset(x.begin(), x.end(),
 		      {})),
diff --git a/libstdc++-v3/testsuite/23_containers/unordered_set/cons/deduction.cc b/libstdc++-v3/testsuite/23_containers/unordered_set/cons/deduction.cc
index a745dce0fba..69922cd92e7 100644
--- a/libstdc++-v3/testsuite/23_containers/unordered_set/cons/deduction.cc
+++ b/libstdc++-v3/testsuite/23_containers/unordered_set/cons/deduction.cc
@@ -9,11 +9,6 @@ static_assert(std::is_same_v<
 	      decltype(std::unordered_set{1, 2, 3}),
 	      std::unordered_set<int>>);
 
-static_assert(std::is_same_v<
-	      decltype(std::unordered_set{{1, 2, 3},
-		    0, std::hash<int>{}, {}}),
-	      std::unordered_set<int>>);
-
 static_assert(std::is_same_v<
 	      decltype(std::unordered_set{{1, 2, 3},
 		    {}}),
@@ -71,11 +66,6 @@ void f()
 		      std::allocator<int>{}}),
 		std::unordered_set<int>>);
 
-  static_assert(std::is_same_v<
-		decltype(std::unordered_set{x.begin(), x.end(),
-		      {}, std::hash<int>{}, {}}),
-		std::unordered_set<int>>);
-
   static_assert(std::is_same_v<
 		decltype(std::unordered_set(x.begin(), x.end(),
 		      {})),
