diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -10016,6 +10016,7 @@
   auto *CaptureInitIt = E->capture_init_begin();
   const LambdaCapture *CaptureIt = ClosureClass->captures_begin();
   bool Success = true;
+  const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(ClosureClass);
   for (const auto *Field : ClosureClass->fields()) {
     assert(CaptureInitIt != E->capture_init_end());
     // Get the initializer for this field
@@ -10026,8 +10027,15 @@
     if (!CurFieldInit)
       return Error(E);
 
+    LValue Subobject = This;
+
+    // FIXME: Diagnostics here should point to the end of the initializer
+    // list, not the start.
+    if (!HandleLValueMember(Info, E, Subobject, Field, &Layout))
+      return false;
+
     APValue &FieldVal = Result.getStructField(Field->getFieldIndex());
-    if (!EvaluateInPlace(FieldVal, Info, This, CurFieldInit)) {
+    if (!EvaluateInPlace(FieldVal, Info, Subobject, CurFieldInit)) {
       if (!Info.keepEvaluatingAfterFailure())
         return false;
       Success = false;
diff --git a/clang/test/SemaCXX/constant-expression-cxx2a.cpp b/clang/test/SemaCXX/constant-expression-cxx2a.cpp
--- a/clang/test/SemaCXX/constant-expression-cxx2a.cpp
+++ b/clang/test/SemaCXX/constant-expression-cxx2a.cpp
@@ -1437,3 +1437,13 @@
   return true;
 }
 static_assert(destroy_at_test());
+
+namespace PR48582 {
+  struct S {
+    void *p = this;
+    constexpr S() {}
+    constexpr S(const S&) {}
+  };
+  constexpr bool b = [a = S(), b = S()] { return a.p == b.p; }();
+  static_assert(!b);
+}