diff --git a/clang/include/clang/Basic/BuiltinsWebAssembly.def b/clang/include/clang/Basic/BuiltinsWebAssembly.def
--- a/clang/include/clang/Basic/BuiltinsWebAssembly.def
+++ b/clang/include/clang/Basic/BuiltinsWebAssembly.def
@@ -211,5 +211,7 @@
 TARGET_BUILTIN(__builtin_wasm_store32_lane, "vi*V4iIi", "n", "simd128")
 TARGET_BUILTIN(__builtin_wasm_store64_lane, "vLLi*V2LLiIi", "n", "simd128")
 
+TARGET_BUILTIN(__builtin_wasm_eq_i64x2, "V2LLiV2LLiV2LLi", "nc", "simd128")
+
 #undef BUILTIN
 #undef TARGET_BUILTIN
diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -16697,6 +16697,12 @@
     Function *Callee = CGM.getIntrinsic(Intrinsic::wasm_popcnt);
     return Builder.CreateCall(Callee, {Vec});
   }
+  case WebAssembly::BI__builtin_wasm_eq_i64x2: {
+    Value *LHS = EmitScalarExpr(E->getArg(0));
+    Value *RHS = EmitScalarExpr(E->getArg(1));
+    Function *Callee = CGM.getIntrinsic(Intrinsic::wasm_eq);
+    return Builder.CreateCall(Callee, {LHS, RHS});
+  }
   case WebAssembly::BI__builtin_wasm_any_true_i8x16:
   case WebAssembly::BI__builtin_wasm_any_true_i16x8:
   case WebAssembly::BI__builtin_wasm_any_true_i32x4:
diff --git a/clang/test/CodeGen/builtins-wasm.c b/clang/test/CodeGen/builtins-wasm.c
--- a/clang/test/CodeGen/builtins-wasm.c
+++ b/clang/test/CodeGen/builtins-wasm.c
@@ -656,6 +656,12 @@
   // WEBASSEMBLY-NEXT: ret
 }
 
+i64x2 eq_i64x2(i64x2 x, i64x2 y) {
+  return __builtin_wasm_eq_i64x2(x, y);
+  // WEBASSEMBLY: call <2 x i64> @llvm.wasm.eq(<2 x i64> %x, <2 x i64> %y)
+  // WEBASSEMBLY-NEXT: ret
+}
+
 int any_true_i8x16(i8x16 x) {
   return __builtin_wasm_any_true_i8x16(x);
   // WEBASSEMBLY: call i32 @llvm.wasm.anytrue.v16i8(<16 x i8> %x)
diff --git a/llvm/include/llvm/IR/IntrinsicsWebAssembly.td b/llvm/include/llvm/IR/IntrinsicsWebAssembly.td
--- a/llvm/include/llvm/IR/IntrinsicsWebAssembly.td
+++ b/llvm/include/llvm/IR/IntrinsicsWebAssembly.td
@@ -294,6 +294,13 @@
             [LLVMMatchType<0>, LLVMMatchType<0>, LLVMMatchType<0>],
             [IntrNoMem, IntrSpeculatable]>;
 
+// TODO: Remove this intrinsic and the associated builtin if i64x2.eq gets
+// merged to the proposal.
+def int_wasm_eq :
+  Intrinsic<[llvm_v2i64_ty],
+            [llvm_v2i64_ty, llvm_v2i64_ty],
+            [IntrNoMem, IntrSpeculatable]>;
+
 //===----------------------------------------------------------------------===//
 // Thread-local storage intrinsics
 //===----------------------------------------------------------------------===//
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
@@ -641,6 +641,14 @@
 def : Pat<(v2i64 (nodes[0] (v2f64 V128:$lhs), (v2f64 V128:$rhs))),
           (v2i64 (nodes[1] (v2f64 V128:$lhs), (v2f64 V128:$rhs)))>;
 
+// Prototype i64x2.eq
+defm EQ_v2i64 :
+  SIMD_I<(outs V128:$dst), (ins V128:$lhs, V128:$rhs), (outs), (ins),
+         [(set (v2i64 V128:$dst),
+           (int_wasm_eq (v2i64 V128:$lhs), (v2i64 V128:$rhs))
+         )],
+         "i64x2.eq\t$dst, $lhs, $rhs", "i64x2.eq", 192>;
+
 
 //===----------------------------------------------------------------------===//
 // Bitwise operations
diff --git a/llvm/test/CodeGen/WebAssembly/simd-intrinsics.ll b/llvm/test/CodeGen/WebAssembly/simd-intrinsics.ll
--- a/llvm/test/CodeGen/WebAssembly/simd-intrinsics.ll
+++ b/llvm/test/CodeGen/WebAssembly/simd-intrinsics.ll
@@ -528,6 +528,16 @@
 ; ==============================================================================
 ; 2 x i64
 ; ==============================================================================
+; CHECK-LABEL: eq_v2i64:
+; SIMD128-NEXT: .functype eq_v2i64 (v128, v128) -> (v128){{$}}
+; SIMD128-NEXT: i64x2.eq $push[[R:[0-9]+]]=, $0, $1{{$}}
+; SIMD128-NEXT: return $pop[[R]]{{$}}
+declare <2 x i64> @llvm.wasm.eq(<2 x i64>, <2 x i64>)
+define <2 x i64> @eq_v2i64(<2 x i64> %x, <2 x i64> %y) {
+  %a = call <2 x i64> @llvm.wasm.eq(<2 x i64> %x, <2 x i64> %y)
+  ret <2 x i64> %a
+}
+
 ; CHECK-LABEL: widen_low_s_v2i64:
 ; SIMD128-NEXT: .functype widen_low_s_v2i64 (v128) -> (v128){{$}}
 ; SIMD128-NEXT: i64x2.widen_low_i32x4_s $push[[R:[0-9]+]]=, $0{{$}}
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
@@ -511,6 +511,9 @@
     # CHECK: i32x4.dot_i16x8_s # encoding: [0xfd,0xba,0x01]
     i32x4.dot_i16x8_s
 
+    # CHECK: i64x2.eq # encoding: [0xfd,0xc0,0x01]
+    i64x2.eq
+
     # CHECK: i64x2.neg # encoding: [0xfd,0xc1,0x01]
     i64x2.neg