Index: lib/CodeGen/CodeGenModule.cpp
===================================================================
--- lib/CodeGen/CodeGenModule.cpp
+++ lib/CodeGen/CodeGenModule.cpp
@@ -3761,8 +3761,11 @@
       }
     }
   }
-  // COFF doesn't support alignments greater than 32, so these cannot be
-  // in common.
+
+  // MSVC doesn't support alignments greater than 32 for common symbols, so
+  // symbols with greater alignment requirements cannot be common. Non-MSVC COFF
+  // environments support arbitrary power-of-two alignments for common symbols
+  // via the aligncomm directive, so the restriction doesn't apply there.
   if (Context.getTargetInfo().getTriple().isKnownWindowsMSVCEnvironment() &&
       Context.getTypeAlignIfKnown(D->getType()) > 32)
     return true;