diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -68,6 +68,9 @@
 - Fixed a crash-on-valid with consteval evaluation of a list-initialized
   constructor for a temporary object. This fixes
   `Issue 55871 <https://github.com/llvm/llvm-project/issues/55871>`_.
+- Fix `#57008 <https://github.com/llvm/llvm-project/issues/57008>`_ - Builtin
+  C++ language extension type traits instantiated by a template with unexpected
+  number of arguments cause an assertion fault.
 
 Improvements to Clang's diagnostics
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/include/clang/Basic/TypeTraits.h b/clang/include/clang/Basic/TypeTraits.h
--- a/clang/include/clang/Basic/TypeTraits.h
+++ b/clang/include/clang/Basic/TypeTraits.h
@@ -67,6 +67,10 @@
 const char *getTraitSpelling(TypeTrait T) LLVM_READONLY;
 const char *getTraitSpelling(ArrayTypeTrait T) LLVM_READONLY;
 const char *getTraitSpelling(UnaryExprOrTypeTrait T) LLVM_READONLY;
+
+/// Return the arity of the type trait \p T.
+unsigned getTypeTraitArity(TypeTrait T) LLVM_READONLY;
+
 } // namespace clang
 
 #endif
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -5552,6 +5552,8 @@
   bool isQualifiedMemberAccess(Expr *E);
   QualType CheckAddressOfOperand(ExprResult &Operand, SourceLocation OpLoc);
 
+  bool CheckTypeTraitArity(unsigned Arity, SourceLocation Loc, size_t N);
+
   ExprResult CreateUnaryExprOrTypeTraitExpr(TypeSourceInfo *TInfo,
                                             SourceLocation OpLoc,
                                             UnaryExprOrTypeTrait ExprKind,
diff --git a/clang/lib/Basic/TypeTraits.cpp b/clang/lib/Basic/TypeTraits.cpp
--- a/clang/lib/Basic/TypeTraits.cpp
+++ b/clang/lib/Basic/TypeTraits.cpp
@@ -55,6 +55,15 @@
 #include "clang/Basic/TokenKinds.def"
 };
 
+static constexpr const unsigned TypeTraitArities[] = {
+#define TYPE_TRAIT_1(Spelling, Name, Key) 1,
+#include "clang/Basic/TokenKinds.def"
+#define TYPE_TRAIT_2(Spelling, Name, Key) 2,
+#include "clang/Basic/TokenKinds.def"
+#define TYPE_TRAIT_N(Spelling, Name, Key) 0,
+#include "clang/Basic/TokenKinds.def"
+};
+
 const char *clang::getTraitName(TypeTrait T) {
   assert(T <= TT_Last && "invalid enum value!");
   return TypeTraitNames[T];
@@ -84,3 +93,8 @@
   assert(T <= UETT_Last && "invalid enum value!");
   return UnaryExprOrTypeTraitSpellings[T];
 }
+
+unsigned clang::getTypeTraitArity(TypeTrait T) {
+  assert(T <= TT_Last && "invalid enum value!");
+  return TypeTraitArities[T];
+}
diff --git a/clang/lib/Parse/ParseExprCXX.cpp b/clang/lib/Parse/ParseExprCXX.cpp
--- a/clang/lib/Parse/ParseExprCXX.cpp
+++ b/clang/lib/Parse/ParseExprCXX.cpp
@@ -3724,14 +3724,6 @@
   }
 }
 
-static unsigned TypeTraitArity(tok::TokenKind kind) {
-  switch (kind) {
-    default: llvm_unreachable("Not a known type trait");
-#define TYPE_TRAIT(N,Spelling,K) case tok::kw_##Spelling: return N;
-#include "clang/Basic/TokenKinds.def"
-  }
-}
-
 /// Parse the built-in type-trait pseudo-functions that allow
 /// implementation of the TR1/C++11 type traits templates.
 ///
@@ -3745,7 +3737,6 @@
 ///
 ExprResult Parser::ParseTypeTrait() {
   tok::TokenKind Kind = Tok.getKind();
-  unsigned Arity = TypeTraitArity(Kind);
 
   SourceLocation Loc = ConsumeToken();
 
@@ -3780,18 +3771,6 @@
 
   SourceLocation EndLoc = Parens.getCloseLocation();
 
-  if (Arity && Args.size() != Arity) {
-    Diag(EndLoc, diag::err_type_trait_arity)
-      << Arity << 0 << (Arity > 1) << (int)Args.size() << SourceRange(Loc);
-    return ExprError();
-  }
-
-  if (!Arity && Args.empty()) {
-    Diag(EndLoc, diag::err_type_trait_arity)
-      << 1 << 1 << 1 << (int)Args.size() << SourceRange(Loc);
-    return ExprError();
-  }
-
   return Actions.ActOnTypeTrait(TypeTraitFromTokKind(Kind), Loc, Args, EndLoc);
 }
 
diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
--- a/clang/lib/Sema/SemaExprCXX.cpp
+++ b/clang/lib/Sema/SemaExprCXX.cpp
@@ -5427,9 +5427,26 @@
 }
 }
 
+bool Sema::CheckTypeTraitArity(unsigned Arity, SourceLocation Loc, size_t N) {
+  if (Arity && N != Arity) {
+    Diag(Loc, diag::err_type_trait_arity)
+        << Arity << 0 << (Arity > 1) << (int)N << SourceRange(Loc);
+    return false;
+  }
+
+  if (!Arity && N == 0) {
+    Diag(Loc, diag::err_type_trait_arity)
+        << 1 << 1 << 1 << (int)N << SourceRange(Loc);
+    return false;
+  }
+  return true;
+}
+
 ExprResult Sema::BuildTypeTrait(TypeTrait Kind, SourceLocation KWLoc,
                                 ArrayRef<TypeSourceInfo *> Args,
                                 SourceLocation RParenLoc) {
+  if (!CheckTypeTraitArity(getTypeTraitArity(Kind), KWLoc, Args.size()))
+    return ExprError();
   QualType ResultType = Context.getLogicalOperationType();
 
   if (Kind <= UTT_Last && !CheckUnaryTypeTraitTypeCompleteness(
diff --git a/clang/test/SemaCXX/type-trait-eval-crash-issue-57008.cpp b/clang/test/SemaCXX/type-trait-eval-crash-issue-57008.cpp
new file mode 100644
--- /dev/null
+++ b/clang/test/SemaCXX/type-trait-eval-crash-issue-57008.cpp
@@ -0,0 +1,6 @@
+// RUN: %clang_cc1 -fsyntax-only %s -verify
+
+// Shouldn't crash here
+// Reported by https://github.com/llvm/llvm-project/issues/57008
+template<class... Ts> bool b = __is_constructible(Ts...); // expected-error{{type trait requires 1 or more arguments}}
+bool x = b<>; // expected-note{{in instantiation of variable template specialization}}