diff --git a/flang/lib/Optimizer/Builder/IntrinsicCall.cpp b/flang/lib/Optimizer/Builder/IntrinsicCall.cpp
index f4541bf30676a6..fe7605d8ce4ba7 100644
--- a/flang/lib/Optimizer/Builder/IntrinsicCall.cpp
+++ b/flang/lib/Optimizer/Builder/IntrinsicCall.cpp
@@ -1059,6 +1059,12 @@ static constexpr MathOperation mathOperations[] = {
     {"atan", "catan", genFuncType<Ty::Complex<8>, Ty::Complex<8>>, genLibCall},
     {"atan", RTNAME_STRING(CAtanF128), FuncTypeComplex16Complex16,
      genLibF128Call},
+    {"atan", "atan2f", genFuncType<Ty::Real<4>, Ty::Real<4>, Ty::Real<4>>,
+     genMathOp<mlir::math::Atan2Op>},
+    {"atan", "atan2", genFuncType<Ty::Real<8>, Ty::Real<8>, Ty::Real<8>>,
+     genMathOp<mlir::math::Atan2Op>},
+    {"atan", RTNAME_STRING(Atan2F128), FuncTypeReal16Real16Real16,
+     genLibF128Call},
     {"atan2", "atan2f", genFuncType<Ty::Real<4>, Ty::Real<4>, Ty::Real<4>>,
      genMathOp<mlir::math::Atan2Op>},
     {"atan2", "atan2", genFuncType<Ty::Real<8>, Ty::Real<8>, Ty::Real<8>>,
diff --git a/flang/test/Lower/Intrinsics/atan.f90 b/flang/test/Lower/Intrinsics/atan.f90
new file mode 100644
index 00000000000000..cf595b4d95d1d4
--- /dev/null
+++ b/flang/test/Lower/Intrinsics/atan.f90
@@ -0,0 +1,55 @@
+! Check that correct runtime calls are used.
+! RUN: bbc --math-runtime=precise -emit-fir %s -o - | FileCheck --check-prefixes=CHECK-RUNTIME %s
+! RUN: %flang_fc1 -mllvm -math-runtime=precise -emit-fir %s -o - | FileCheck --check-prefixes=CHECK-RUNTIME %s
+
+! Check that the correct math dialect operations are used.
+! RUN: bbc -emit-fir %s -o - | FileCheck --check-prefixes=CHECK-NORMAL %s
+! RUN: %flang_fc1 -emit-fir %s -o - | FileCheck --check-prefixes=CHECK-NORMAL %s
+
+function test_real4(x)
+  real :: x, test_real4
+  test_real4 = atan(x)
+end function
+
+! CHECK-RUNTIME: {{%[A-Za-z0-9._]+}} = fir.call @atanf({{.*}}) {{.*}}: (f32) -> f32
+! CHECK-NORMAL: {{%[A-Za-z0-9._]+}} = math.atan {{.*}} {{.*}}: f32
+
+function test_real8(x)
+  real(8) :: x, test_real8
+  test_real8 = atan(x)
+end function
+
+! CHECK-RUNTIME: {{%[A-Za-z0-9._]+}} = fir.call @atan({{.*}}) {{.*}}: (f64) -> f64
+! CHECK-NORMAL: {{%[A-Za-z0-9._]+}} = math.atan {{.*}} {{.*}}: f64
+
+function test_complex4(x)
+  complex :: x, test_complex4
+  test_complex4 = atan(x)
+end function
+
+! CHECK-RUNTIME: {{%[A-Za-z0-9._]+}} = fir.call @catanf({{.*}}) {{.*}}: (!fir.complex<4>) -> !fir.complex<4>
+! CHECK-NORMAL: {{%[A-Za-z0-9._]+}} = fir.call @catanf({{.*}}) {{.*}}: (!fir.complex<4>) -> !fir.complex<4>
+
+function test_complex8(x)
+  complex(kind=8) :: x, test_complex8
+  test_complex8 = atan(x)
+end function
+
+! CHECK-RUNTIME: {{%[A-Za-z0-9._]+}} = fir.call @catan({{.*}}) {{.*}}: (!fir.complex<8>) -> !fir.complex<8>
+! CHECK-NORMAL: {{%[A-Za-z0-9._]+}} = fir.call @catan({{.*}}) {{.*}}: (!fir.complex<8>) -> !fir.complex<8>
+
+function test_real4_2(y, x)
+  real :: y, x, test_real4_2
+  test_real4_2 = atan(y, x)
+end function
+
+! CHECK-RUNTIME: {{%[A-Za-z0-9._]+}} = fir.call @atan2f({{.*}}) {{.*}}: (f32, f32) -> f32
+! CHECK-NORMAL: {{%[A-Za-z0-9._]+}} = math.atan2 {{.*}} {{.*}}: f32
+
+function test_real8_2(y, x)
+  real(8) :: y, x, test_real8_2
+  test_real8_2 = atan(y, x)
+end function
+
+! CHECK-RUNTIME: {{%[A-Za-z0-9._]+}} = fir.call @atan2({{.*}}) {{.*}}: (f64, f64) -> f64
+! CHECK-NORMAL: {{%[A-Za-z0-9._]+}} = math.atan2 {{.*}} {{.*}}: f64
diff --git a/flang/test/Lower/Intrinsics/atan_real16.f90 b/flang/test/Lower/Intrinsics/atan_real16.f90
index 5c0c262711c61b..3ae037307c32b6 100644
--- a/flang/test/Lower/Intrinsics/atan_real16.f90
+++ b/flang/test/Lower/Intrinsics/atan_real16.f90
@@ -3,7 +3,18 @@
 ! RUN: bbc --math-runtime=precise -emit-fir %s -o - | FileCheck %s
 ! RUN: %flang_fc1 -emit-fir %s -o - | FileCheck %s
 
+function test_real16(x)
+  real(16) :: x, test_real16
+  test_real16 = atan(x)
+end function real16
+
+! CHECK-LABEL: @_QPtest_real16
 ! CHECK: fir.call @_FortranAAtanF128({{.*}}){{.*}}: (f128) -> f128
-  real(16) :: a, b
-  b = atan(a)
-end
+
+function test_real16_2(y, x)
+  real(16) :: y, x, test_real16
+  test_real16 = atan(y, x)
+end function real16_2
+
+! CHECK-LABEL: @_QPtest_real16
+! CHECK: fir.call @_FortranAAtan2F128({{.*}}){{.*}}: (f128, f128) -> f128