Index: llvm/lib/IR/Globals.cpp
===================================================================
--- llvm/lib/IR/Globals.cpp
+++ llvm/lib/IR/Globals.cpp
@@ -65,6 +65,7 @@
 void GlobalValue::copyAttributesFrom(const GlobalValue *Src) {
   setVisibility(Src->getVisibility());
   setUnnamedAddr(Src->getUnnamedAddr());
+  setThreadLocalMode(Src->getThreadLocalMode());
   setDLLStorageClass(Src->getDLLStorageClass());
   setDSOLocal(Src->isDSOLocal());
   setPartition(Src->getPartition());
@@ -419,7 +420,6 @@
 /// from the GlobalVariable Src to this one.
 void GlobalVariable::copyAttributesFrom(const GlobalVariable *Src) {
   GlobalObject::copyAttributesFrom(Src);
-  setThreadLocalMode(Src->getThreadLocalMode());
   setExternallyInitialized(Src->isExternallyInitialized());
   setAttributes(Src->getAttributes());
 }
Index: llvm/test/Linker/Inputs/alias-threadlocal-defs.ll
===================================================================
--- /dev/null
+++ llvm/test/Linker/Inputs/alias-threadlocal-defs.ll
@@ -0,0 +1,2 @@
+@tlsvar1 = thread_local global i32 0, align 4
+@tlsvar2 = hidden thread_local alias i32, i32* @tlsvar1
Index: llvm/test/Linker/alias-threadlocal.ll
===================================================================
--- /dev/null
+++ llvm/test/Linker/alias-threadlocal.ll
@@ -0,0 +1,9 @@
+; RUN: llvm-link %s %p/Inputs/alias-threadlocal-defs.ll -S -o - | FileCheck %s
+
+; PR46297
+; Verify that linking GlobalAliases preserves the thread_local attribute
+
+; CHECK: @tlsvar1 = thread_local global i32 0, align 4
+; CHECK: @tlsvar2 = hidden thread_local alias i32, i32* @tlsvar1
+
+@tlsvar2 = external thread_local global i32, align 4