Index: clang/lib/AST/Interp/ByteCodeExprGen.h
===================================================================
--- clang/lib/AST/Interp/ByteCodeExprGen.h
+++ clang/lib/AST/Interp/ByteCodeExprGen.h
@@ -35,6 +35,7 @@
 template <class Emitter> class DeclScope;
 template <class Emitter> class OptionScope;
 template <class Emitter> class ArrayIndexScope;
+template <class Emitter> class SourceLocScope;
 
 /// Compilation context for expressions.
 template <class Emitter>
@@ -100,6 +101,7 @@
   bool VisitPredefinedExpr(const PredefinedExpr *E);
   bool VisitCXXThrowExpr(const CXXThrowExpr *E);
   bool VisitCXXReinterpretCastExpr(const CXXReinterpretCastExpr *E);
+  bool VisitSourceLocExpr(const SourceLocExpr *E);
 
 protected:
   bool visitExpr(const Expr *E) override;
@@ -148,6 +150,8 @@
   bool visitRecordInitializer(const Expr *Initializer);
   /// Creates and initializes a variable from the given decl.
   bool visitVarDecl(const VarDecl *VD);
+  /// Visit an APValue.
+  bool visitAPValue(const APValue &Val, PrimType ValType, const Expr *E);
 
   /// Visits an expression and converts it to a boolean.
   bool visitBool(const Expr *E);
@@ -207,6 +211,7 @@
   friend class DeclScope<Emitter>;
   friend class OptionScope<Emitter>;
   friend class ArrayIndexScope<Emitter>;
+  friend class SourceLocScope<Emitter>;
 
   /// Emits a zero initializer.
   bool visitZeroInitializer(QualType QT, const Expr *E);
@@ -235,12 +240,14 @@
                       llvm::function_ref<bool(PrimType)> Indirect);
 
   /// Emits an APSInt constant.
+  bool emitConst(const llvm::APSInt &Value, PrimType Ty, const Expr *E);
   bool emitConst(const llvm::APSInt &Value, const Expr *E);
   bool emitConst(const llvm::APInt &Value, const Expr *E) {
     return emitConst(static_cast<llvm::APSInt>(Value), E);
   }
 
   /// Emits an integer constant.
+  template <typename T> bool emitConst(T Value, PrimType Ty, const Expr *E);
   template <typename T> bool emitConst(T Value, const Expr *E);
 
   /// Returns the CXXRecordDecl for the type of the given expression,
@@ -281,6 +288,9 @@
   /// Current argument index. Needed to emit ArrayInitIndexExpr.
   std::optional<uint64_t> ArrayIndex;
 
+  /// DefaultInit- or DefaultArgExpr, needed for SourceLocExpr.
+  const Expr *SourceLocDefaultExpr = nullptr;
+
   /// Flag indicating if return value is to be discarded.
   bool DiscardResult = false;
 };
@@ -436,6 +446,28 @@
   std::optional<uint64_t> OldArrayIndex;
 };
 
+template <class Emitter> class SourceLocScope final {
+public:
+  SourceLocScope(ByteCodeExprGen<Emitter> *Ctx, const Expr *DefaultExpr)
+      : Ctx(Ctx) {
+    assert(DefaultExpr);
+    // We only switch if the current SourceLocDefaultExpr is null.
+    if (!Ctx->SourceLocDefaultExpr) {
+      Enabled = true;
+      Ctx->SourceLocDefaultExpr = DefaultExpr;
+    }
+  }
+
+  ~SourceLocScope() {
+    if (Enabled)
+      Ctx->SourceLocDefaultExpr = nullptr;
+  }
+
+private:
+  ByteCodeExprGen<Emitter> *Ctx;
+  bool Enabled = false;
+};
+
 } // namespace interp
 } // namespace clang
 
Index: clang/lib/AST/Interp/ByteCodeExprGen.cpp
===================================================================
--- clang/lib/AST/Interp/ByteCodeExprGen.cpp
+++ clang/lib/AST/Interp/ByteCodeExprGen.cpp
@@ -1138,6 +1138,62 @@
   return this->emitInvalidCast(CastKind::Reinterpret, E);
 }
 
+template <class Emitter>
+bool ByteCodeExprGen<Emitter>::VisitSourceLocExpr(const SourceLocExpr *E) {
+  if (DiscardResult)
+    return true;
+
+  const APValue Val =
+      E->EvaluateInContext(Ctx.getASTContext(), SourceLocDefaultExpr);
+
+  // Things like __builtin_LINE().
+  if (E->getType()->isIntegerType()) {
+    assert(Val.isInt());
+    const APSInt &I = Val.getInt();
+    return this->emitConst(I, E);
+  }
+  // Otherwise, the APValue is an LValue, with only one element.
+  // Theoretically, we don't need the APValue at all of course.
+  assert(E->getType()->isPointerType());
+  assert(Val.isLValue());
+  const APValue::LValueBase &Base = Val.getLValueBase();
+  if (const Expr *LValueExpr = Base.dyn_cast<const Expr *>())
+    return this->visit(LValueExpr);
+
+  // Otherwise, we have a decl (which is the case for
+  // __builtin_source_location).
+  assert(Base.is<const ValueDecl *>());
+  assert(Val.getLValuePath().size() == 0);
+  const auto *BaseDecl = Base.dyn_cast<const ValueDecl *>();
+  assert(BaseDecl);
+
+  auto *UGCD = cast<UnnamedGlobalConstantDecl>(BaseDecl);
+
+  std::optional<unsigned> GlobalIndex = P.getOrCreateGlobal(UGCD);
+  if (!GlobalIndex)
+    return false;
+
+  if (!this->emitGetPtrGlobal(*GlobalIndex, E))
+    return false;
+
+  const Record *R = getRecord(E->getType());
+  const APValue &V = UGCD->getValue();
+  for (unsigned I = 0, N = R->getNumFields(); I != N; ++I) {
+    const Record::Field *F = R->getField(I);
+    const APValue &FieldValue = V.getStructField(I);
+
+    PrimType FieldT = classifyPrim(F->Decl->getType());
+
+    if (!this->visitAPValue(FieldValue, FieldT, E))
+      return false;
+    if (!this->emitInitField(FieldT, F->Offset, E))
+      return false;
+  }
+
+  // Leave the pointer to the global on the stack.
+  return true;
+}
+
 template <class Emitter> bool ByteCodeExprGen<Emitter>::discard(const Expr *E) {
   if (E->containsErrors())
     return false;
@@ -1384,8 +1440,8 @@
 
 template <class Emitter>
 template <typename T>
-bool ByteCodeExprGen<Emitter>::emitConst(T Value, const Expr *E) {
-  switch (classifyPrim(E->getType())) {
+bool ByteCodeExprGen<Emitter>::emitConst(T Value, PrimType Ty, const Expr *E) {
+  switch (Ty) {
   case PT_Sint8:
     return this->emitConstSint8(Value, E);
   case PT_Uint8:
@@ -1414,10 +1470,22 @@
 }
 
 template <class Emitter>
-bool ByteCodeExprGen<Emitter>::emitConst(const APSInt &Value, const Expr *E) {
+template <typename T>
+bool ByteCodeExprGen<Emitter>::emitConst(T Value, const Expr *E) {
+  return this->emitConst(Value, classifyPrim(E->getType()), E);
+}
+
+template <class Emitter>
+bool ByteCodeExprGen<Emitter>::emitConst(const APSInt &Value, PrimType Ty,
+                                         const Expr *E) {
   if (Value.isSigned())
-    return this->emitConst(Value.getSExtValue(), E);
-  return this->emitConst(Value.getZExtValue(), E);
+    return this->emitConst(Value.getSExtValue(), Ty, E);
+  return this->emitConst(Value.getZExtValue(), Ty, E);
+}
+
+template <class Emitter>
+bool ByteCodeExprGen<Emitter>::emitConst(const APSInt &Value, const Expr *E) {
+  return this->emitConst(Value, classifyPrim(E->getType()), E);
 }
 
 template <class Emitter>
@@ -1722,6 +1790,7 @@
 
     return this->visit(CE);
   } else if (const auto *DIE = dyn_cast<CXXDefaultInitExpr>(Initializer)) {
+    SourceLocScope<Emitter> SLS(this, DIE);
     return this->visitInitializer(DIE->getExpr());
   } else if (const auto *BBCE = dyn_cast<BuiltinBitCastExpr>(Initializer)) {
     return this->visit(BBCE);
@@ -1901,6 +1970,22 @@
   return false;
 }
 
+template <class Emitter>
+bool ByteCodeExprGen<Emitter>::visitAPValue(const APValue &Val,
+                                            PrimType ValType, const Expr *E) {
+  assert(!DiscardResult);
+  if (Val.isInt())
+    return this->emitConst(Val.getInt(), ValType, E);
+
+  if (Val.isLValue()) {
+    APValue::LValueBase Base = Val.getLValueBase();
+    if (const Expr *BaseExpr = Base.dyn_cast<const Expr *>())
+      return this->visit(BaseExpr);
+  }
+
+  return false;
+}
+
 template <class Emitter>
 bool ByteCodeExprGen<Emitter>::VisitBuiltinCallExpr(const CallExpr *E) {
   const Function *Func = getFunction(E->getDirectCallee());
@@ -2014,14 +2099,16 @@
 bool ByteCodeExprGen<Emitter>::VisitCXXDefaultInitExpr(
     const CXXDefaultInitExpr *E) {
   assert(classify(E->getType()));
+  SourceLocScope<Emitter> SLS(this, E);
   return this->visit(E->getExpr());
 }
 
 template <class Emitter>
 bool ByteCodeExprGen<Emitter>::VisitCXXDefaultArgExpr(
     const CXXDefaultArgExpr *E) {
-  const Expr *SubExpr = E->getExpr();
+  SourceLocScope<Emitter> SLS(this, E);
 
+  const Expr *SubExpr = E->getExpr();
   if (std::optional<PrimType> T = classify(E->getExpr()))
     return this->visit(SubExpr);
 
Index: clang/lib/AST/Interp/Program.cpp
===================================================================
--- clang/lib/AST/Interp/Program.cpp
+++ clang/lib/AST/Interp/Program.cpp
@@ -161,9 +161,12 @@
                                               const Expr *Init) {
   assert(!getGlobal(VD));
   bool IsStatic, IsExtern;
-  if (auto *Var = dyn_cast<VarDecl>(VD)) {
+  if (const auto *Var = dyn_cast<VarDecl>(VD)) {
     IsStatic = Context::shouldBeGloballyIndexed(VD);
     IsExtern = !Var->getAnyInitializer();
+  } else if (isa<UnnamedGlobalConstantDecl>(VD)) {
+    IsStatic = true;
+    IsExtern = false;
   } else {
     IsStatic = false;
     IsExtern = true;
Index: clang/test/AST/Interp/builtin-functions.cpp
===================================================================
--- clang/test/AST/Interp/builtin-functions.cpp
+++ clang/test/AST/Interp/builtin-functions.cpp
@@ -133,3 +133,31 @@
   _Complex double CD = __arithmetic_fence(CD);
 #endif
 }
+
+namespace std {
+struct source_location {
+  struct __impl {
+    unsigned int _M_line;
+    const char *_M_file_name;
+    signed char _M_column;
+    const char *_M_function_name;
+  };
+  using BuiltinT = decltype(__builtin_source_location()); // OK.
+};
+}
+
+namespace SourceLocation {
+  constexpr auto A = __builtin_source_location();
+  static_assert(A->_M_line == 150, "");
+  static_assert(A->_M_column == 22, "");
+  static_assert(__builtin_strcmp(A->_M_function_name, "") == 0, "");
+  static_assert(__builtin_strcmp(A->_M_file_name, __FILE__) == 0, "");
+
+  static_assert(__builtin_LINE() == 156, "");
+
+  struct Foo {
+    int a = __builtin_LINE();
+  };
+
+  static_assert(Foo{}.a == 162, "");
+}