diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyInstrSIMD.td b/llvm/lib/Target/WebAssembly/WebAssemblyInstrSIMD.td
--- a/llvm/lib/Target/WebAssembly/WebAssemblyInstrSIMD.td
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyInstrSIMD.td
@@ -832,7 +832,7 @@
 defm ALLTRUE : SIMDReduce<int_wasm_alltrue, "all_true", 99>;
 
 // Population count: popcnt
-defm POPCNT : SIMDUnary<I8x16, int_wasm_popcnt, "popcnt", 124>;
+defm POPCNT : SIMDUnary<I8x16, int_wasm_popcnt, "popcnt", 0x62>;
 
 // Reductions already return 0 or 1, so and 1, setne 0, and seteq 1
 // can be folded out
diff --git a/llvm/test/MC/WebAssembly/simd-encodings.s b/llvm/test/MC/WebAssembly/simd-encodings.s
--- a/llvm/test/MC/WebAssembly/simd-encodings.s
+++ b/llvm/test/MC/WebAssembly/simd-encodings.s
@@ -324,7 +324,8 @@
     # CHECK: i8x16.neg # encoding: [0xfd,0x61]
     i8x16.neg
 
-    # TODO: i8x16.popcnt # encoding: [0xfd,0x62]
+    # CHECK: i8x16.popcnt # encoding: [0xfd,0x62]
+    i8x16.popcnt
 
     # CHECK: i8x16.all_true # encoding: [0xfd,0x63]
     i8x16.all_true