diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -59,6 +59,8 @@
 - Improved ``-O0`` code generation for calls to ``std::forward_like``. Similarly to
   ``std::move, std::forward`` et al. it is now treated as a compiler builtin and implemented
   directly rather than instantiating the definition from the standard library.
+- Implemented `CWG2518 <https://wg21.link/CWG2518>`_ which allows ``static_assert(false)``
+  to not be ill-formed when its condition is evaluated in the context of a template definition.
 
 C++20 Feature Support
 ^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -16799,7 +16799,14 @@
                        FoldKind).isInvalid())
       Failed = true;
 
-    if (!Failed && !Cond) {
+    // CWG2518
+    // [dcl.pre]/p10  If [...] the expression is evaluated in the context of a
+    // template definition, the declaration has no effect.
+    bool InTemplateDefinition =
+        getLangOpts().CPlusPlus && CurContext->isDependentContext();
+
+    if (!Failed && !Cond && !InTemplateDefinition) {
+
       SmallString<256> MsgBuffer;
       llvm::raw_svector_ostream Msg(MsgBuffer);
       if (AssertMessage) {
@@ -16830,7 +16837,8 @@
         DiagnoseStaticAssertDetails(InnerCond);
       } else {
         Diag(StaticAssertLoc, diag::err_static_assert_failed)
-          << !AssertMessage << Msg.str() << AssertExpr->getSourceRange();
+            << !AssertMessage << Msg.str() << AssertExpr->getSourceRange();
+        PrintContextStack();
       }
       Failed = true;
     }
diff --git a/clang/test/CXX/drs/dr25xx.cpp b/clang/test/CXX/drs/dr25xx.cpp
--- a/clang/test/CXX/drs/dr25xx.cpp
+++ b/clang/test/CXX/drs/dr25xx.cpp
@@ -1,5 +1,50 @@
 // RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-unknown %s -verify
 
+namespace dr2518 { // dr2518: 17 review
+
+#error one
+// expected-error@-1 {{one}}
+#if 0
+#error skip
+#warning skip
+#endif
+#error two
+// expected-error@-1 {{two}}
+#warning warn
+// expected-warning@-1 {{warn}}
+
+template <class T>
+void f(T t) {
+  if constexpr (sizeof(T) != sizeof(int)) {
+    static_assert(false, "must be int-sized"); // expected-error {{must be int-size}}
+  }
+}
+
+void g(char c) {
+  f(0);
+  f(c); // expected-note {{requested here}}
+}
+
+template <typename Ty>
+struct S {
+  static_assert(false); // expected-error {{static assertion failed}}
+};
+
+template <>
+struct S<int> {};
+
+template <>
+struct S<float> {};
+
+int test_specialization() {
+  S<int> s1;
+  S<float> s2;
+  S<double> s3; // expected-note {{in instantiation of template class 'dr2518::S<double>' requested here}}
+}
+
+}
+
+
 namespace dr2565 { // dr2565: 16 open
   template<typename T>
     concept C = requires (typename T::type x) {
diff --git a/clang/test/SemaCXX/access-base-class.cpp b/clang/test/SemaCXX/access-base-class.cpp
--- a/clang/test/SemaCXX/access-base-class.cpp
+++ b/clang/test/SemaCXX/access-base-class.cpp
@@ -96,14 +96,14 @@
 };
 
 template <class T>
-struct trait : flag<sizeof(T)> {};
+struct trait : flag<sizeof(T)> {}; // expected-note 2{{here}}
 
-template <class T, bool Inferred = trait<T>::value>
+template <class T, bool Inferred = trait<T>::value> // expected-note {{here}}
 struct a {};
 
 template <class T>
 class b {
-  a<T> x;
+  a<T> x; // expected-note {{here}}
   using U = a<T>;
 };
 
@@ -113,5 +113,5 @@
 };
 
 // verify "no member named 'value'" bogus diagnostic is not emitted.
-trait<b<Impossible<0>>>::value;
+trait<b<Impossible<0>>>::value; // expected-note {{here}}
 } // namespace T8
diff --git a/clang/test/SemaCXX/coroutines-exp-namespace.cpp b/clang/test/SemaCXX/coroutines-exp-namespace.cpp
--- a/clang/test/SemaCXX/coroutines-exp-namespace.cpp
+++ b/clang/test/SemaCXX/coroutines-exp-namespace.cpp
@@ -1288,7 +1288,7 @@
   }
 };
 
-template struct DepTestType<int>; // expected-note {{requested here}}
+template struct DepTestType<int>; // expected-note 2{{requested here}}
 template CoroMemberTag DepTestType<int>::test_member_template(long, const char *) const &&;
 
 template CoroMemberTag DepTestType<int>::test_static_template<void>(const char *volatile &, unsigned);
diff --git a/clang/test/SemaCXX/coroutines.cpp b/clang/test/SemaCXX/coroutines.cpp
--- a/clang/test/SemaCXX/coroutines.cpp
+++ b/clang/test/SemaCXX/coroutines.cpp
@@ -1309,7 +1309,7 @@
   }
 };
 
-template struct DepTestType<int>; // expected-note {{requested here}}
+template struct DepTestType<int>; // expected-note 2{{requested here}}
 template CoroMemberTag DepTestType<int>::test_member_template(long, const char *) const &&;
 
 template CoroMemberTag DepTestType<int>::test_static_template<void>(const char *volatile &, unsigned);
diff --git a/clang/test/SemaCXX/static-assert.cpp b/clang/test/SemaCXX/static-assert.cpp
--- a/clang/test/SemaCXX/static-assert.cpp
+++ b/clang/test/SemaCXX/static-assert.cpp
@@ -52,9 +52,11 @@
 
 template<typename T> struct AlwaysFails {
   // Only give one error here.
-  static_assert(false, ""); // expected-error {{static assertion failed}}
+  static_assert(false, ""); // expected-error 2{{static assertion failed}}
 };
-AlwaysFails<int> alwaysFails;
+AlwaysFails<int> alwaysFails; // expected-note {{instantiation}}
+AlwaysFails<double> alwaysFails2; // expected-note {{instantiation}}
+
 
 template<typename T> struct StaticAssertProtected {
   static_assert(__is_literal(T), ""); // expected-error {{static assertion failed}}
@@ -217,6 +219,23 @@
 
 static_assert(1 , "") // expected-error {{expected ';' after 'static_assert'}}
 
+namespace DependentAlwaysFalse {
+template <typename Ty>
+struct S {
+  static_assert(false); // expected-error{{static assertion failed}} \
+                        // expected-warning {{C++17 extension}}
+};
+
+template <typename Ty>
+struct T {
+  static_assert(false, "test"); // expected-error{{static assertion failed: test}}
+};
+
+int f() {
+  S<double> s; //expected-note {{in instantiation of template class 'DependentAlwaysFalse::S<double>' requested here}}
+  T<double> t; //expected-note {{in instantiation of template class 'DependentAlwaysFalse::T<double>' requested here}}
+}
+}
 
 namespace Diagnostics {
   /// No notes for literals.
diff --git a/clang/test/SemaTemplate/instantiate-var-template.cpp b/clang/test/SemaTemplate/instantiate-var-template.cpp
--- a/clang/test/SemaTemplate/instantiate-var-template.cpp
+++ b/clang/test/SemaTemplate/instantiate-var-template.cpp
@@ -31,9 +31,9 @@
   static_assert(b<char> == 1, ""); // expected-note {{in instantiation of}}
 
   template<typename T> void f() {
-    static_assert(a<sizeof(sizeof(f(T())))> == 0, ""); // expected-error {{static assertion failed due to requirement 'a<sizeof (sizeof (f(type-parameter-0-0())))> == 0'}} \
-                                                       // expected-note {{evaluates to '1 == 0'}}
+    int check[a<sizeof(sizeof(f(T())))> == 0 ? 1 : -1]; // expected-error {{array with a negative size}}
   }
+
 }
 
 namespace PR24483 {
diff --git a/clang/test/SemaTemplate/instantiation-dependence.cpp b/clang/test/SemaTemplate/instantiation-dependence.cpp
--- a/clang/test/SemaTemplate/instantiation-dependence.cpp
+++ b/clang/test/SemaTemplate/instantiation-dependence.cpp
@@ -37,8 +37,8 @@
   template<class ...Args> using indirect_void_t = typename indirect_void_t_imp<Args...>::type;
 
   template<class T> void foo() {
-    static_assert(!__is_void(indirect_void_t<T>)); // "ok", dependent
-    static_assert(!__is_void(void_t<T>)); // expected-error {{failed}}
+    int check1[__is_void(indirect_void_t<T>) == 0 ? 1 : -1]; // "ok", dependent
+    int check2[__is_void(void_t<T>) == 0 ? 1 : -1]; // expected-error {{array with a negative size}}
   }
 }
 
diff --git a/clang/www/cxx_dr_status.html b/clang/www/cxx_dr_status.html
--- a/clang/www/cxx_dr_status.html
+++ b/clang/www/cxx_dr_status.html
@@ -14915,7 +14915,7 @@
     <td><a href="https://wg21.link/cwg2518">2518</a></td>
     <td>review</td>
     <td>Conformance requirements and <TT>#error</TT>/<TT>#warning</TT></td>
-    <td align="center">Not resolved</td>
+    <td class="unreleased" align="center">Clang 17</td>
   </tr>
   <tr class="open" id="2519">
     <td><a href="https://wg21.link/cwg2519">2519</a></td>