diff --git a/llvm/lib/MC/MCParser/AsmParser.cpp b/llvm/lib/MC/MCParser/AsmParser.cpp
--- a/llvm/lib/MC/MCParser/AsmParser.cpp
+++ b/llvm/lib/MC/MCParser/AsmParser.cpp
@@ -3354,6 +3354,10 @@
   if (parseEOL())
     return true;
 
+  if (FillSize == 0) {
+    Warning(SizeLoc, "'.fill' directive with 0 size has no effect");
+    return false;
+  }
   if (FillSize < 0) {
     Warning(SizeLoc, "'.fill' directive with negative size has no effect");
     return false;