diff --git a/lld/MachO/Writer.cpp b/lld/MachO/Writer.cpp
--- a/lld/MachO/Writer.cpp
+++ b/lld/MachO/Writer.cpp
@@ -960,6 +960,12 @@
           segname == segment_names::text)
         osec->align = target->wordSize;
 
+      // MC keeps the default 1-byte alignment for __thread_vars, even though it
+      // contains pointers that are fixed up by dyld, which requires proper
+      // alignment.
+      if (isThreadLocalVariables(osec->flags))
+        osec->align = std::max<uint32_t>(osec->align, target->wordSize);
+
       getOrCreateOutputSegment(segname)->addOutputSection(osec);
     }
   }
diff --git a/lld/test/MachO/tlv-dylib.s b/lld/test/MachO/tlv-dylib.s
--- a/lld/test/MachO/tlv-dylib.s
+++ b/lld/test/MachO/tlv-dylib.s
@@ -43,7 +43,7 @@
 # FLAGS-NEXT:      addr
 # FLAGS-NEXT:      size 0x0000000000000030
 # FLAGS-NEXT:    offset
-# FLAGS-NEXT:     align
+# FLAGS-NEXT:     align 2^3 (8)
 # FLAGS-NEXT:    reloff 0
 # FLAGS-NEXT:    nreloc 0
 # FLAGS-NEXT:      type S_THREAD_LOCAL_VARIABLES