diff --git a/llvm/lib/Target/X86/X86InstrSSE.td b/llvm/lib/Target/X86/X86InstrSSE.td
index 0f782c9a8fde..829f65c4623f 100644
--- a/llvm/lib/Target/X86/X86InstrSSE.td
+++ b/llvm/lib/Target/X86/X86InstrSSE.td
@@ -2417,6 +2417,10 @@ def LFENCE : I<0xAE, MRM_E8, (outs), (ins),
 def MFENCE : I<0xAE, MRM_F0, (outs), (ins),
                "mfence", [(int_x86_sse2_mfence)]>, TB, Requires<[HasSSE2]>;
 
+// Pause. This "instruction" is encoded as "rep; nop", so even though it
+// was introduced with SSE2, it's backward compabitle.
+def PAUSE : I<0x90, RawFrm, (outs), (ins), "pause", []>, REP;
+
 //TODO: custom lower this so as to never even generate the noop
 def : Pat<(membarrier (i8 imm), (i8 imm), (i8 imm), (i8 imm),
            (i8 0)), (NOOP)>;
diff --git a/llvm/test/MC/AsmParser/X86/x86_32-bit_cat.s b/llvm/test/MC/AsmParser/X86/x86_32-bit_cat.s
index ec2bfa4a913d..c1efe293c00a 100644
--- a/llvm/test/MC/AsmParser/X86/x86_32-bit_cat.s
+++ b/llvm/test/MC/AsmParser/X86/x86_32-bit_cat.s
@@ -2482,6 +2482,12 @@
 // CHECK: 	clflush	305419896
         	clflush	0x12345678
 
+// CHECK: 	pause
+        	pause
+
+// CHECK: 	sfence
+        	sfence
+
 // CHECK: 	lfence
         	lfence
 
diff --git a/llvm/test/MC/AsmParser/X86/x86_32-new-encoder.s b/llvm/test/MC/AsmParser/X86/x86_32-new-encoder.s
index 2400f5ad0125..6c087761671e 100644
--- a/llvm/test/MC/AsmParser/X86/x86_32-new-encoder.s
+++ b/llvm/test/MC/AsmParser/X86/x86_32-new-encoder.s
@@ -1,5 +1,8 @@
 // RUN: llvm-mc -triple i386-unknown-unknown --show-encoding %s | FileCheck %s
 
+	pause
+// CHECK: pause
+// CHECK: encoding: [0xf3,0x90]
 	sfence
 // CHECK: sfence
 // CHECK: encoding: [0x0f,0xae,0xf8]