diff --git a/lib/Target/X86/X86InstrSSE.td b/lib/Target/X86/X86InstrSSE.td
index 5d32fb8f68e..b912949d482 100644
--- a/lib/Target/X86/X86InstrSSE.td
+++ b/lib/Target/X86/X86InstrSSE.td
@@ -3673,6 +3673,14 @@ let Uses = [ECX, EAX] in
 def MWAITrr   : I<0x01, MRM_C9, (outs), (ins), "mwait", []>, TB,
                 Requires<[HasSSE3]>;
 
+def : InstAlias<"mwait %eax, %ecx", (MWAITrr)>, Requires<[In32BitMode]>;
+def : InstAlias<"mwait %rax, %rcx", (MWAITrr)>, Requires<[In64BitMode]>;
+
+def : InstAlias<"monitor %eax, %ecx, %edx", (MONITORrrr)>,
+      Requires<[In32BitMode]>;
+def : InstAlias<"monitor %rax, %rcx, %rdx", (MONITORrrr)>,
+      Requires<[In64BitMode]>;
+
 //===---------------------------------------------------------------------===//
 // Non-Instruction Patterns
 //===---------------------------------------------------------------------===//
diff --git a/test/MC/X86/x86-32.s b/test/MC/X86/x86-32.s
index 9ff5accf194..de6b96389ea 100644
--- a/test/MC/X86/x86-32.s
+++ b/test/MC/X86/x86-32.s
@@ -14,9 +14,15 @@
 // CHECK: encoding: [0x0f,0xae,0xf0]
 	monitor
 // CHECK: monitor
+// CHECK: encoding: [0x0f,0x01,0xc8]
+	monitor %eax, %ecx, %edx
+// CHECK: monitor
 // CHECK: encoding: [0x0f,0x01,0xc8]
 	mwait
 // CHECK: mwait
+// CHECK: encoding: [0x0f,0x01,0xc9]
+	mwait %eax, %ecx
+// CHECK: mwait
 // CHECK: encoding: [0x0f,0x01,0xc9]
 
 	vmcall
diff --git a/test/MC/X86/x86-64.s b/test/MC/X86/x86-64.s
index ed3162c0a98..b1fc9accfd1 100644
--- a/test/MC/X86/x86-64.s
+++ b/test/MC/X86/x86-64.s
@@ -2,6 +2,18 @@
 // RUN: FileCheck < %t %s
 // RUN: FileCheck --check-prefix=CHECK-STDERR < %t.err %s
 
+	monitor
+// CHECK: monitor
+// CHECK: encoding: [0x0f,0x01,0xc8]
+	monitor %rax, %rcx, %rdx
+// CHECK: monitor
+// CHECK: encoding: [0x0f,0x01,0xc8]
+	mwait
+// CHECK: mwait
+// CHECK: encoding: [0x0f,0x01,0xc9]
+	mwait %rax, %rcx
+// CHECK: mwait
+// CHECK: encoding: [0x0f,0x01,0xc9]
 
 // Suffix inference: