diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index b510fa5034891..e13de5ecb8d15 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -338,6 +338,8 @@ Bug Fixes to C++ Support
 - Fix the parsing of variadic member functions when the ellipis immediately follows a default argument.(#GH153445)
 - Fixed a bug that caused ``this`` captured by value in a lambda with a dependent explicit object parameter to not be
   instantiated properly. (#GH154054)
+- Fixed a crash when implicit conversions from initialize list to arrays of
+  unknown bound during constant evaluation. (#GH151716)
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 66362d44976c4..f0592b0cd51c2 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -4030,10 +4030,12 @@ findSubobject(EvalInfo &Info, const Expr *E, const CompleteObject &Obj,
     LastField = nullptr;
     if (ObjType->isArrayType()) {
       // Next subobject is an array element.
-      const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(ObjType);
-      assert(CAT && "vla in literal type?");
+      const ArrayType *AT = Info.Ctx.getAsArrayType(ObjType);
+      assert((isa<ConstantArrayType>(AT) || isa<IncompleteArrayType>(AT)) &&
+             "vla in literal type?");
       uint64_t Index = Sub.Entries[I].getAsArrayIndex();
-      if (CAT->getSize().ule(Index)) {
+      if (const auto *CAT = dyn_cast<ConstantArrayType>(AT);
+          CAT && CAT->getSize().ule(Index)) {
         // Note, it should not be possible to form a pointer with a valid
         // designator which points more than one past the end of the array.
         if (Info.getLangOpts().CPlusPlus11)
@@ -4044,12 +4046,13 @@ findSubobject(EvalInfo &Info, const Expr *E, const CompleteObject &Obj,
         return handler.failed();
       }
 
-      ObjType = CAT->getElementType();
+      ObjType = AT->getElementType();
 
       if (O->getArrayInitializedElts() > Index)
         O = &O->getArrayInitializedElt(Index);
       else if (!isRead(handler.AccessKind)) {
-        if (!CheckArraySize(Info, CAT, E->getExprLoc()))
+        if (const auto *CAT = dyn_cast<ConstantArrayType>(AT);
+            CAT && !CheckArraySize(Info, CAT, E->getExprLoc()))
           return handler.failed();
 
         expandArray(*O, Index);
diff --git a/clang/test/CodeGenCXX/cxx20-p0388-unbound-ary.cpp b/clang/test/CodeGenCXX/cxx20-p0388-unbound-ary.cpp
index a29f4d720c1de..007b47c441b2f 100644
--- a/clang/test/CodeGenCXX/cxx20-p0388-unbound-ary.cpp
+++ b/clang/test/CodeGenCXX/cxx20-p0388-unbound-ary.cpp
@@ -32,4 +32,19 @@ void foo(int a) {
   f({a});
 }
 
+constexpr int gh151716() {
+  int(&&g)[]{0,1,2};
+  return g[2];
+}
+// CHECK-LABEL: @_ZN3One10gh151716_fEv
+// CHECK-NEXT: entry:
+// CHECK-NEXT:   %v = alloca i32, align 4
+// CHECK-NEXT:   call void @llvm.lifetime.start.p0(ptr nonnull %v)
+// CHECK-NEXT:   store volatile i32 2, ptr %v, align 4
+// CHECK-NEXT:   call void @llvm.lifetime.end.p0(ptr nonnull %v)
+// CHECK-NEXT:   ret void
+void gh151716_f() {
+  volatile const int v = gh151716();
+}
+
 } // namespace One