diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -1009,13 +1009,15 @@
   // objects than Args. This copies an Arg from one of those other InputArgLists
   // to the ownership of Args.
   auto appendOneArg = [&Args](const Arg *Opt, const Arg *BaseArg) {
-      unsigned Index = Args.MakeIndex(Opt->getSpelling());
-      Arg *Copy = new llvm::opt::Arg(Opt->getOption(), Opt->getSpelling(),
-                                     Index, BaseArg);
-      Copy->getValues() = Opt->getValues();
-      if (Opt->isClaimed())
-        Copy->claim();
-      Args.append(Copy);
+    unsigned Index = Args.MakeIndex(Opt->getSpelling());
+    Arg *Copy = new llvm::opt::Arg(Opt->getOption(), Args.getArgString(Index),
+                                   Index, BaseArg);
+    Copy->getValues() = Opt->getValues();
+    if (Opt->isClaimed())
+      Copy->claim();
+    Copy->setOwnsValues(Opt->getOwnsValues());
+    Opt->setOwnsValues(false);
+    Args.append(Copy);
   };
 
   if (HasConfigFile)
diff --git a/clang/test/Driver/cl-options.c b/clang/test/Driver/cl-options.c
--- a/clang/test/Driver/cl-options.c
+++ b/clang/test/Driver/cl-options.c
@@ -686,6 +686,11 @@
 // CLANG-NOT: "--dependent-lib=libcmt"
 // CLANG-NOT: "-vectorize-slp"
 
+// Cover PR42501: clang-cl /clang: pass-through causes read-after-free with aliased options.
+// RUN: %clang_cl /clang:-save-temps /clang:-Wl,test1,test2 -### -- %s 2>&1 | FileCheck -check-prefix=SAVETEMPS %s
+// SAVETEMPS: "-save-temps=cwd"
+// SAVETEMPS: "test1" "test2"
+
 // Validate that the default triple is used when run an empty tools dir is specified
 // RUN: %clang_cl -vctoolsdir "" -### -- %s 2>&1 | FileCheck %s --check-prefix VCTOOLSDIR
 // VCTOOLSDIR: "-triple" "{{[a-zA-Z0-9_-]*}}-pc-windows-msvc19.11.0"