diff --git a/clang/lib/CIR/CodeGen/CIRGenAtomic.cpp b/clang/lib/CIR/CodeGen/CIRGenAtomic.cpp
index d8981c8c7ca56..3b78e6e22d2a7 100644
--- a/clang/lib/CIR/CodeGen/CIRGenAtomic.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenAtomic.cpp
@@ -159,9 +159,9 @@ bool AtomicInfo::requiresMemSetZero(mlir::Type ty) const {
   case cir::TEK_Scalar:
     return !isFullSizeType(cgf.cgm, ty, atomicSizeInBits);
   case cir::TEK_Complex:
-    cgf.cgm.errorNYI(loc, "AtomicInfo::requiresMemSetZero: complex type");
-    return false;
-
+    return !isFullSizeType(cgf.cgm,
+                           mlir::cast<cir::ComplexType>(ty).getElementType(),
+                           atomicSizeInBits / 2);
   // Padding in structs has an undefined bit pattern.  User beware.
   case cir::TEK_Aggregate:
     return false;
@@ -556,9 +556,11 @@ void CIRGenFunction::emitAtomicInit(Expr *init, LValue dest) {
     return;
   }
 
-  case cir::TEK_Complex:
-    cgm.errorNYI(init->getSourceRange(), "emitAtomicInit: complex type");
+  case cir::TEK_Complex: {
+    mlir::Value value = emitComplexExpr(init);
+    atomics.emitCopyIntoMemory(RValue::get(value));
     return;
+  }
 
   case cir::TEK_Aggregate:
     cgm.errorNYI(init->getSourceRange(), "emitAtomicInit: aggregate type");
diff --git a/clang/test/CIR/CodeGen/complex.cpp b/clang/test/CIR/CodeGen/complex.cpp
index db837e568e0be..2e1198b09f010 100644
--- a/clang/test/CIR/CodeGen/complex.cpp
+++ b/clang/test/CIR/CodeGen/complex.cpp
@@ -909,3 +909,21 @@ void foo33(__builtin_va_list a) {
 // OGCG:  %[[B_IMAG_PTR:.*]] = getelementptr inbounds nuw { float, float }, ptr %[[B_ADDR]], i32 0, i32 1
 // OGCG:  store float %[[RESULT_REAL]], ptr %[[B_REAL_PTR]], align 4
 // OGCG:  store float %[[RESULT_IMAG]], ptr %[[B_IMAG_PTR]], align 4
+
+void foo34() {
+  _Atomic(float _Complex) a;
+  __c11_atomic_init(&a, {1.0f, 2.0f});
+}
+
+// CIR: %[[A_ADDR:.*]] = cir.alloca !cir.complex<!cir.float>, !cir.ptr<!cir.complex<!cir.float>>, ["a"]
+// CIR: %[[CONST_COMPLEX:.*]] = cir.const #cir.const_complex<#cir.fp<1.000000e+00> : !cir.float, #cir.fp<2.000000e+00> : !cir.float> : !cir.complex<!cir.float>
+// CIR: cir.store{{.*}} %[[CONST_COMPLEX]], %[[A_ADDR]] : !cir.complex<!cir.float>, !cir.ptr<!cir.complex<!cir.float>>
+
+// LLVM: %[[A_ADDR:.*]] = alloca { float, float }, i64 1, align 8
+// LLVM: store { float, float } { float 1.000000e+00, float 2.000000e+00 }, ptr %[[A_ADDR]], align 8
+
+// OGCG: %[[A_ADDR:.*]] = alloca { float, float }, align 8
+// OGCG: %[[A_REAL_PTR:.*]] = getelementptr inbounds nuw { float, float }, ptr %[[A_ADDR]], i32 0, i32 0
+// OGCG: %[[A_IMAG_PTR:.*]] = getelementptr inbounds nuw { float, float }, ptr %[[A_ADDR]], i32 0, i32 1
+// OGCG: store float 1.000000e+00, ptr %[[A_REAL_PTR]], align 8
+// OGCG: store float 2.000000e+00, ptr %[[A_IMAG_PTR]], align 4