diff --git a/llvm/utils/extract_symbols.py b/llvm/utils/extract_symbols.py
--- a/llvm/utils/extract_symbols.py
+++ b/llvm/utils/extract_symbols.py
@@ -88,6 +88,7 @@
                 yield name
     process.wait()
 
+
 # Define functions which determine if the target is 32-bit Windows (as that's
 # where calling convention name decoration happens).
 
@@ -126,6 +127,11 @@
             return (match.group(1) == 'COFF-i386')
     return False
 
+# If we are relying on nm, then we are not targeting windows,
+# always return false.
+def nm_is_32bit_windows(lib):
+    return False
+
 # MSVC mangles names to ?<identifier_mangling>@<type_mangling>. By examining the
 # identifier/type mangling we can decide which symbols could possibly be
 # required and which we can discard.
@@ -353,7 +359,7 @@
     # Determine the function to use to get the list of symbols from the inputs,
     # and the function to use to determine if the target is 32-bit windows.
     tools = { 'dumpbin' : (dumpbin_get_symbols, dumpbin_is_32bit_windows),
-              'nm' : (nm_get_symbols, None),
+              'nm' : (nm_get_symbols, nm_is_32bit_windows),
               'objdump' : (None, objdump_is_32bit_windows),
               'llvm-readobj' : (readobj_get_symbols, readobj_is_32bit_windows) }
     get_symbols = None