diff --git a/llvm/lib/MC/MCParser/MasmParser.cpp b/llvm/lib/MC/MCParser/MasmParser.cpp
--- a/llvm/lib/MC/MCParser/MasmParser.cpp
+++ b/llvm/lib/MC/MCParser/MasmParser.cpp
@@ -2440,6 +2440,8 @@
   const StringRef nextVal = nextTok.getString();
   const SMLoc nextLoc = nextTok.getLoc();
 
+  const AsmToken peekTok = Lexer.peekTok();
+
   // There are several entities interested in parsing infix directives:
   //
   // 1. Asm parser extensions. For example, platform-specific parsers
@@ -2483,25 +2485,55 @@
     Lex();
     return parseDirectiveEquate(nextVal, IDVal, DirKind);
   case DK_BYTE:
+    if (peekTok.is(AsmToken::Identifier) &&
+        peekTok.getString().equals_lower("ptr")) {
+      // Size directive; part of an instruction.
+      break;
+    }
+    LLVM_FALLTHROUGH;
   case DK_SBYTE:
   case DK_DB:
     Lex();
     return parseDirectiveNamedValue(nextVal, 1, IDVal, IDLoc);
   case DK_WORD:
+    if (peekTok.is(AsmToken::Identifier) &&
+        peekTok.getString().equals_lower("ptr")) {
+      // Size directive; part of an instruction.
+      break;
+    }
+    LLVM_FALLTHROUGH;
   case DK_SWORD:
   case DK_DW:
     Lex();
     return parseDirectiveNamedValue(nextVal, 2, IDVal, IDLoc);
   case DK_DWORD:
+    if (peekTok.is(AsmToken::Identifier) &&
+        peekTok.getString().equals_lower("ptr")) {
+      // Size directive; part of an instruction.
+      break;
+    }
+    LLVM_FALLTHROUGH;
   case DK_SDWORD:
   case DK_DD:
     Lex();
     return parseDirectiveNamedValue(nextVal, 4, IDVal, IDLoc);
   case DK_FWORD:
+    if (peekTok.is(AsmToken::Identifier) &&
+        peekTok.getString().equals_lower("ptr")) {
+      // Size directive; part of an instruction.
+      break;
+    }
+    LLVM_FALLTHROUGH;
   case DK_DF:
     Lex();
     return parseDirectiveNamedValue(nextVal, 6, IDVal, IDLoc);
   case DK_QWORD:
+    if (peekTok.is(AsmToken::Identifier) &&
+        peekTok.getString().equals_lower("ptr")) {
+      // Size directive; part of an instruction.
+      break;
+    }
+    LLVM_FALLTHROUGH;
   case DK_SQWORD:
   case DK_DQ:
     Lex();