diff --git a/clang/include/clang/AST/ExprConcepts.h b/clang/include/clang/AST/ExprConcepts.h
--- a/clang/include/clang/AST/ExprConcepts.h
+++ b/clang/include/clang/AST/ExprConcepts.h
@@ -423,12 +423,13 @@
   }
 
   NestedRequirement(ASTContext &C, Expr *Constraint,
-                    const ConstraintSatisfaction &Satisfaction) :
-      Requirement(RK_Nested, Constraint->isInstantiationDependent(),
-                  Constraint->containsUnexpandedParameterPack(),
-                  Satisfaction.IsSatisfied),
-      Value(Constraint),
-      Satisfaction(ASTConstraintSatisfaction::Create(C, Satisfaction)) {}
+                    const ConstraintSatisfaction &Satisfaction)
+      : Requirement(RK_Nested,
+                    Constraint && Constraint->isInstantiationDependent(),
+                    Constraint && Constraint->containsUnexpandedParameterPack(),
+                    Satisfaction.IsSatisfied),
+        Value(Constraint),
+        Satisfaction(ASTConstraintSatisfaction::Create(C, Satisfaction)) {}
 
   bool isSubstitutionFailure() const {
     return Value.is<SubstitutionDiagnostic *>();
diff --git a/clang/lib/Sema/SemaConcept.cpp b/clang/lib/Sema/SemaConcept.cpp
--- a/clang/lib/Sema/SemaConcept.cpp
+++ b/clang/lib/Sema/SemaConcept.cpp
@@ -161,7 +161,7 @@
       return ExprError();
 
     bool IsLHSSatisfied = Satisfaction.IsSatisfied;
-
+    
     if (BO.isOr() && IsLHSSatisfied)
       // [temp.constr.op] p3
       //    A disjunction is a constraint taking two operands. To determine if
@@ -286,7 +286,8 @@
           // bool if this is the operand of an '&&' or '||'. For example, we
           // might lose an lvalue-to-rvalue conversion here. If so, put it back
           // before we try to evaluate.
-          if (!SubstitutedExpression.isInvalid())
+          if (SubstitutedExpression.isUsable() &&
+              !SubstitutedExpression.isInvalid())
             SubstitutedExpression =
                 S.PerformContextuallyConvertToBool(SubstitutedExpression.get());
           if (SubstitutedExpression.isInvalid() || Trap.hasErrorOccurred()) {
@@ -316,7 +317,7 @@
             Satisfaction.Details.emplace_back(
                 AtomicExpr,
                 new (S.Context) ConstraintSatisfaction::SubstitutionDiagnostic{
-                        SubstDiag.first, StringRef(Mem, MessageSize)});
+                    SubstDiag.first, StringRef(Mem, MessageSize)});
             Satisfaction.IsSatisfied = false;
             return ExprEmpty();
           }
diff --git a/clang/lib/Sema/SemaTemplateInstantiate.cpp b/clang/lib/Sema/SemaTemplateInstantiate.cpp
--- a/clang/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiate.cpp
@@ -2328,8 +2328,12 @@
         Req->getConstraintExpr()->getSourceRange());
     if (ConstrInst.isInvalid())
       return nullptr;
-    TransConstraint = TransformExpr(Req->getConstraintExpr());
-    if (!TransConstraint.isInvalid()) {
+    llvm::SmallVector<Expr *> Result;
+    if (SemaRef.CheckConstraintSatisfaction(
+            nullptr, {Req->getConstraintExpr()}, Result, TemplateArgs,
+            Req->getConstraintExpr()->getSourceRange(), Satisfaction))
+      TransConstraint = Result[0];
+    if (TransConstraint.isUsable() && !TransConstraint.isInvalid()) {
       bool CheckSucceeded =
           SemaRef.CheckConstraintExpression(TransConstraint.get());
       (void)CheckSucceeded;
@@ -2338,7 +2342,7 @@
                                    "did not produce a SFINAE error");
     }
     // Use version of CheckConstraintSatisfaction that does no substitutions.
-    if (!TransConstraint.isInvalid() &&
+    if (TransConstraint.isUsable() && !TransConstraint.isInvalid() &&
         !TransConstraint.get()->isInstantiationDependent() &&
         !Trap.hasErrorOccurred()) {
       bool CheckFailed = SemaRef.CheckConstraintSatisfaction(
@@ -2355,7 +2359,8 @@
                                                     SemaRef.getPrintingPolicy());
           }));
   }
-  if (TransConstraint.get()->isInstantiationDependent())
+  if (TransConstraint.isUsable() &&
+      TransConstraint.get()->isInstantiationDependent())
     return new (SemaRef.Context)
         concepts::NestedRequirement(TransConstraint.get());
   return new (SemaRef.Context) concepts::NestedRequirement(
diff --git a/clang/test/CXX/expr/expr.prim/expr.prim.req/nested-requirement.cpp b/clang/test/CXX/expr/expr.prim/expr.prim.req/nested-requirement.cpp
--- a/clang/test/CXX/expr/expr.prim/expr.prim.req/nested-requirement.cpp
+++ b/clang/test/CXX/expr/expr.prim/expr.prim.req/nested-requirement.cpp
@@ -19,7 +19,8 @@
 
 template<typename T>
 struct X {
-    template<typename U> requires requires (U u) { requires sizeof(u) == sizeof(T); } // expected-note{{because 'sizeof (u) == sizeof(T)' would be invalid: invalid application of 'sizeof' to an incomplete type 'void'}}
+    template<typename U> requires requires (U u) { requires sizeof(u) == sizeof(T); } 
+    // expected-note@-1 {{because substituted constraint expression is ill-formed: invalid application of 'sizeof' to an incomplete type 'void'}}
     struct r4 {};
 };
 
@@ -41,7 +42,7 @@
   template<typename T>
   concept C2 = requires (T a) {
       requires sizeof(a) == 4; // OK
-      requires a == 0; // expected-note{{because 'a == 0' would be invalid: constraint variable 'a' cannot be used in an evaluated context}}
+      requires a == 0; // expected-note{{because substituted constraint expression is ill-formed: constraint variable 'a' cannot be used in an evaluated context}}
     };
   static_assert(C2<int>); // expected-note{{because 'int' does not satisfy 'C2'}} expected-error{{static assertion failed}}
 }
@@ -51,3 +52,90 @@
   X.next();
 };
 
+namespace SubstitutionFailureNestedRequires {
+template<class T>  concept True = true;
+
+struct S { double value; };
+
+template <class T>
+concept Pipes = requires (T x) {
+   requires True<decltype(x.value)> || True<T>;
+   requires True<T> || True<decltype(x.value)>;
+};
+
+template <class T>
+concept Amps1 = requires (T x) {
+   requires True<decltype(x.value)> && True<T>;
+   // expected-note@-1{{because substituted constraint expression is ill-formed: member reference base type 'int' is not a structure or union}}
+};
+template <class T>
+concept Amps2 = requires (T x) {
+   requires True<T> && True<decltype(x.value)>;
+};
+
+static_assert(Pipes<S>);
+static_assert(Pipes<double>);
+
+static_assert(Amps1<S>);
+static_assert(!Amps1<double>);
+
+static_assert(Amps2<S>);
+static_assert(!Amps2<double>);
+
+template<class T>
+void foo1() requires requires (T x) { // expected-note {{candidate template ignored: constraints not satisfied [with T = int]}}
+  requires
+  True<decltype(x.value)> // expected-note {{because substituted constraint expression is ill-formed: member reference base type 'int' is not a structure or union}}
+  && True<T>;
+} {}
+template<class T> void fooPipes() requires Pipes<T> {}
+template<class T> void fooAmps1() requires Amps1<T> {}
+// expected-note@-1 {{candidate template ignored: constraints not satisfied [with T = int]}} \
+// expected-note@-1 {{because 'int' does not satisfy 'Amps1'}}
+
+void foo() {
+  foo1<S>();
+  foo1<int>(); // expected-error {{no matching function for call to 'foo1'}}
+  fooPipes<S>();
+  fooPipes<int>();
+  fooAmps1<S>();
+  fooAmps1<int>(); // expected-error {{no matching function for call to 'fooAmps1'}}
+}
+
+template<class T>
+concept HasNoValue = requires (T x) {
+  requires !True<decltype(x.value)> && True<T>;
+};
+// FIXME: 'int' does not satisfy 'HasNoValue' currently since `!True<decltype(x.value)>` is an invalid expression.
+// But, in principle, it should be constant-evaluated to true.
+static_assert(!HasNoValue<int>);
+static_assert(!HasNoValue<S>);
+
+template<class T> constexpr bool NotAConceptTrue = true;
+template <class T>
+concept SFinNestedRequires = requires (T x) {
+    // SF in a non-concept specialisation should also be evaluated to false.
+   requires NotAConceptTrue<decltype(x.value)> || NotAConceptTrue<T>;
+};
+static_assert(SFinNestedRequires<int>);
+static_assert(SFinNestedRequires<S>);
+template <class T>
+void foo() requires SFinNestedRequires<T> {} 
+void bar() { 
+  foo<int>();
+  foo<S>();
+}
+namespace SFINAEWithoutConcept {
+  //Add more TODO(usx).
+template<typename T> struct X { static constexpr bool value = T::value; };
+struct True { static constexpr bool value = true; };
+template<typename T> concept C = true;
+
+template<typename T> requires requires(T) { requires C<T> || X<T>::value; } void foo();
+
+void func() {
+  foo<True>();
+  foo<int>(); 
+}
+}
+}
\ No newline at end of file
diff --git a/clang/test/SemaTemplate/instantiate-requires-expr.cpp b/clang/test/SemaTemplate/instantiate-requires-expr.cpp
--- a/clang/test/SemaTemplate/instantiate-requires-expr.cpp
+++ b/clang/test/SemaTemplate/instantiate-requires-expr.cpp
@@ -24,8 +24,8 @@
 
 template<typename T> requires
 false_v<requires (T t) { requires is_same_v<decltype(t), int>; }>
-// expected-note@-1 {{because 'false_v<requires (int t) { requires is_same_v<decltype(t), int>; }>' evaluated to false}}
-// expected-note@-2 {{because 'false_v<requires (char t) { requires is_same_v<decltype(t), int>; }>' evaluated to false}}
+// expected-note@-1 {{because 'false_v<requires (int t) { requires <null expr>; }>' evaluated to false}}
+// expected-note@-2 {{because 'false_v<requires (char t) { requires <null expr>; }>' evaluated to false}}
 struct r1 {};
 
 using r1i1 = r1<int>; // expected-error {{constraints not satisfied for class template 'r1' [with T = int]}}
@@ -35,8 +35,8 @@
 
 template<typename... Ts> requires
 false_v<requires (Ts... ts) {requires ((sizeof(ts) == 2) && ...);}>
-// expected-note@-1 {{because 'false_v<requires (short ts, unsigned short ts) { requires (sizeof (ts) == 2) && (sizeof (ts) == 2); }>'}}
-// expected-note@-2 {{because 'false_v<requires (short ts) { requires (sizeof (ts) == 2); }>' evaluated to false}}
+// expected-note@-1 {{because 'false_v<requires (short ts, unsigned short ts) { requires <null expr>; }>' evaluated to false}}
+// expected-note@-2 {{because 'false_v<requires (short ts) { requires <null expr>; }>' evaluated to false}}
 struct r2 {};
 
 using r2i1 = r2<short, unsigned short>; // expected-error {{constraints not satisfied for class template 'r2' [with Ts = <short, unsigned short>]}}
@@ -44,8 +44,8 @@
 
 template<typename... Ts> requires
 false_v<(requires (Ts ts) {requires sizeof(ts) != 0;} && ...)>
-// expected-note@-1 {{because 'false_v<requires (short ts) { requires sizeof (ts) != 0; } && requires (unsigned short ts) { requires sizeof (ts) != 0; }>' evaluated to false}}
-// expected-note@-2 {{because 'false_v<requires (short ts) { requires sizeof (ts) != 0; }>' evaluated to false}}
+// expected-note@-1 {{because 'false_v<requires (short ts) { requires <null expr>; } && requires (unsigned short ts) { requires <null expr>; }>' evaluated to false}}
+// expected-note@-2 {{because 'false_v<requires (short ts) { requires <null expr>; }>' evaluated to false}}
 struct r3 {};
 
 using r3i1 = r3<short, unsigned short>; // expected-error {{constraints not satisfied for class template 'r3' [with Ts = <short, unsigned short>]}}
@@ -181,7 +181,7 @@
 
 namespace nested_requirement {
   // check that constraint expression is instantiated correctly
-  template<typename T> requires false_v<requires { requires sizeof(T) == 2; }> // expected-note{{because 'false_v<requires { requires sizeof(int) == 2; }>' evaluated to false}}
+  template<typename T> requires false_v<requires { requires sizeof(T) == 2; }> // expected-note{{because 'false_v<requires { requires <null expr>; }>' evaluated to false}}
   struct r1 {};
 
   using r1i = r1<int>; // expected-error{{constraints not satisfied for class template 'r1' [with T = int]}}
@@ -190,7 +190,7 @@
   template<typename T>
   struct a {
       template<typename U> requires
-      (requires { requires sizeof(T::a) == 0; }, false) // expected-note{{because 'requires { requires <<error-expression>>; } , false' evaluated to false}}
+      (requires { requires sizeof(T::a) == 0; }, false) // expected-note{{because 'requires { requires <null expr>; } , false' evaluated to false}}
       struct r {};
   };
 
@@ -199,7 +199,7 @@
   // Parameter pack inside expr
   template<typename... Ts> requires
   false_v<(requires { requires sizeof(Ts) == 0; } && ...)>
-  // expected-note@-1 {{because 'false_v<requires { requires sizeof(int) == 0; } && requires { requires sizeof(short) == 0; }>' evaluated to false}}
+  // expected-note@-1 {{because 'false_v<requires { requires <null expr>; } && requires { requires <null expr>; }>' evaluated to false}}
   struct r2 {};
 
   using r2i = r2<int, short>; // expected-error{{constraints not satisfied for class template 'r2' [with Ts = <int, short>]}}
@@ -208,14 +208,14 @@
 // Parameter pack inside multiple requirements
 template<typename... Ts> requires
 false_v<(requires { requires sizeof(Ts) == 0; sizeof(Ts); } && ...)>
-// expected-note@-1 {{because 'false_v<requires { requires sizeof(int) == 0; sizeof(Ts); } && requires { requires sizeof(short) == 0; sizeof(Ts); }>' evaluated to false}}
+// expected-note@-1 {{because 'false_v<requires { requires <null expr>; sizeof(Ts); } && requires { requires <null expr>; sizeof(Ts); }>' evaluated to false}}
 struct r4 {};
 
 using r4i = r4<int, short>; // expected-error{{constraints not satisfied for class template 'r4' [with Ts = <int, short>]}}
 
 template<typename... Ts> requires
 false_v<(requires(Ts t) { requires sizeof(t) == 0; t++; } && ...)>
-// expected-note@-1 {{because 'false_v<requires (int t) { requires sizeof (t) == 0; t++; } && requires (short t) { requires sizeof (t) == 0; t++; }>' evaluated to false}}
+// expected-note@-1 {{because 'false_v<requires (int t) { requires <null expr>; t++; } && requires (short t) { requires <null expr>; t++; }>' evaluated to false}}
 struct r5 {};
 
 using r5i = r5<int, short>; // expected-error{{constraints not satisfied for class template 'r5' [with Ts = <int, short>]}}