diff --git a/llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp b/llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp
--- a/llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp
+++ b/llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp
@@ -1073,8 +1073,11 @@
 }
 
 unsigned X86AsmBackend::getMaximumNopSize() const {
-  if (!STI.hasFeature(X86::FeatureNOPL) && !STI.hasFeature(X86::Mode64Bit))
+  if (!STI.hasFeature(X86::FeatureNOPL) && !STI.hasFeature(X86::Mode64Bit) &&
+      !STI.hasFeature(X86::Mode16Bit))
     return 1;
+  if (STI.getFeatureBits()[X86::Mode16Bit])
+    return 4;
   if (STI.getFeatureBits()[X86::FeatureFast7ByteNOP])
     return 7;
   if (STI.getFeatureBits()[X86::FeatureFast15ByteNOP])
@@ -1091,29 +1094,44 @@
 /// bytes.
 /// \return - true on success, false on failure
 bool X86AsmBackend::writeNopData(raw_ostream &OS, uint64_t Count) const {
-  static const char Nops[10][11] = {
-    // nop
-    "\x90",
-    // xchg %ax,%ax
-    "\x66\x90",
-    // nopl (%[re]ax)
-    "\x0f\x1f\x00",
-    // nopl 0(%[re]ax)
-    "\x0f\x1f\x40\x00",
-    // nopl 0(%[re]ax,%[re]ax,1)
-    "\x0f\x1f\x44\x00\x00",
-    // nopw 0(%[re]ax,%[re]ax,1)
-    "\x66\x0f\x1f\x44\x00\x00",
-    // nopl 0L(%[re]ax)
-    "\x0f\x1f\x80\x00\x00\x00\x00",
-    // nopl 0L(%[re]ax,%[re]ax,1)
-    "\x0f\x1f\x84\x00\x00\x00\x00\x00",
-    // nopw 0L(%[re]ax,%[re]ax,1)
-    "\x66\x0f\x1f\x84\x00\x00\x00\x00\x00",
-    // nopw %cs:0L(%[re]ax,%[re]ax,1)
-    "\x66\x2e\x0f\x1f\x84\x00\x00\x00\x00\x00",
+  static const char Nops32Bit[10][11] = {
+      // nop
+      "\x90",
+      // xchg %ax,%ax
+      "\x66\x90",
+      // nopl (%[re]ax)
+      "\x0f\x1f\x00",
+      // nopl 0(%[re]ax)
+      "\x0f\x1f\x40\x00",
+      // nopl 0(%[re]ax,%[re]ax,1)
+      "\x0f\x1f\x44\x00\x00",
+      // nopw 0(%[re]ax,%[re]ax,1)
+      "\x66\x0f\x1f\x44\x00\x00",
+      // nopl 0L(%[re]ax)
+      "\x0f\x1f\x80\x00\x00\x00\x00",
+      // nopl 0L(%[re]ax,%[re]ax,1)
+      "\x0f\x1f\x84\x00\x00\x00\x00\x00",
+      // nopw 0L(%[re]ax,%[re]ax,1)
+      "\x66\x0f\x1f\x84\x00\x00\x00\x00\x00",
+      // nopw %cs:0L(%[re]ax,%[re]ax,1)
+      "\x66\x2e\x0f\x1f\x84\x00\x00\x00\x00\x00",
   };
 
+  // 16-bit mode uses different nop patterns than 32-bit.
+  static const char Nops16Bit[4][11] = {
+      // nop
+      "\x90",
+      // xchg %eax,%eax
+      "\x66\x90",
+      // lea 0(%si),%si
+      "\x8d\x74\x00",
+      // lea 0w(%si),%si
+      "\x8d\xb4\x00\x00",
+  };
+
+  const char(*Nops)[11] =
+      STI.getFeatureBits()[X86::Mode16Bit] ? Nops16Bit : Nops32Bit;
+
   uint64_t MaxNopLength = (uint64_t)getMaximumNopSize();
 
   // Emit as many MaxNopLength NOPs as needed, then emit a NOP of the remaining
diff --git a/llvm/test/MC/X86/code16gcc-align.s b/llvm/test/MC/X86/code16gcc-align.s
new file mode 100644
--- /dev/null
+++ b/llvm/test/MC/X86/code16gcc-align.s
@@ -0,0 +1,40 @@
+# RUN: llvm-mc -filetype=obj -triple=i386-unknown-unknown-code16 %s | llvm-objdump --triple=i386-unknown-unknown-code16 -d - | FileCheck %s
+
+# Ensure that the "movzbl" is aligned such that the prefixes 0x67 0x66 are
+# properly included in the "movz" instruction.
+
+# CHECK-LABEL: <test>:
+# CHECK:           1c: 8d b4 00 00                  	leaw	(%si), %si
+# CHECK-NEXT:      20: 66 90                        	nop
+# CHECK-NEXT:      22: 66 89 c7                     	movl	%eax, %edi
+# CHECK-NEXT:      25: 66 31 db                     	xorl	%ebx, %ebx
+# CHECK-NEXT:      28: 8d b4 00 00                  	leaw	(%si), %si
+# CHECK-NEXT:      2c: 8d b4 00 00                      leaw	(%si), %si
+# CHECK-NEXT:      30: 67 66 0f b6 0c 1e            	movzbl	(%esi,%ebx), %ecx
+# CHECK-NEXT:      36: 66 e8 14 00 00 00            	calll	0x50 <called>
+# CHECK-NEXT:      3c: 8d 74 00                     	leaw	(%si), %si
+
+# CHECK-LABEL: <called>:
+# CHECK-NEXT:      50: 90                           	nop
+# CHECK-NEXT:      51: 66 c3                        	retl
+
+	.text
+	.code16gcc
+	.globl	test
+	.p2align	4, 0x90
+	.type	test,@function
+test:
+	.nops	34
+	movl	%eax, %edi
+	xorl	%ebx, %ebx
+	.p2align	4, 0x90
+	movzbl	(%esi,%ebx), %ecx
+	calll	called
+	.nops	3
+	retl
+
+	.p2align	4, 0x90
+	.type	called,@function
+called:
+	.nops	1
+	retl