diff --git a/flang/lib/Optimizer/CodeGen/Target.cpp b/flang/lib/Optimizer/CodeGen/Target.cpp
index 374308fa5894..7dbf21ce0c12 100644
--- a/flang/lib/Optimizer/CodeGen/Target.cpp
+++ b/flang/lib/Optimizer/CodeGen/Target.cpp
@@ -784,7 +784,7 @@ struct TargetX86_64Win : public GenericTarget<TargetX86_64Win> {
 } // namespace
 
 //===----------------------------------------------------------------------===//
-// AArch64 linux target specifics.
+// AArch64 target specifics.
 //===----------------------------------------------------------------------===//
 
 namespace {
@@ -810,6 +810,34 @@ struct TargetAArch64 : public GenericTarget<TargetAArch64> {
     return marshal;
   }
 
+  CodeGenSpecifics::Marshalling
+  integerArgumentType(mlir::Location loc,
+                      mlir::IntegerType argTy) const override {
+    if (argTy.getWidth() < getCIntTypeWidth() && argTy.isSignless()) {
+      AT::IntegerExtension intExt;
+      if (argTy.getWidth() == 1) {
+        // Zero extend for 'i1'.
+        intExt = AT::IntegerExtension::Zero;
+      } else {
+        if (triple.isOSDarwin()) {
+          // On Darwin, sign extend. The apple developer guide specifies this as
+          // a divergence from the AArch64PCS:
+          // https://developer.apple.com/documentation/xcode/writing-arm64-code-for-apple-platforms#Pass-arguments-to-functions-correctly
+          intExt = AT::IntegerExtension::Sign;
+        } else {
+          // On linux, pass directly and do not extend.
+          intExt = AT::IntegerExtension::None;
+        }
+      }
+      CodeGenSpecifics::Marshalling marshal;
+      marshal.emplace_back(argTy, AT{/*alignment=*/0, /*byval=*/false,
+                                     /*sret=*/false, /*append=*/false,
+                                     /*intExt=*/intExt});
+      return marshal;
+    }
+    return GenericTarget::integerArgumentType(loc, argTy);
+  }
+
   CodeGenSpecifics::Marshalling
   complexReturnType(mlir::Location loc, mlir::Type eleTy) const override {
     CodeGenSpecifics::Marshalling marshal;
diff --git a/flang/test/Fir/convert-to-llvm-target.fir b/flang/test/Fir/convert-to-llvm-target.fir
index bb873080072f..6adc5cd4b737 100644
--- a/flang/test/Fir/convert-to-llvm-target.fir
+++ b/flang/test/Fir/convert-to-llvm-target.fir
@@ -1,7 +1,7 @@
 // RUN: fir-opt --split-input-file --fir-to-llvm-ir="target=x86_64-unknown-linux-gnu" %s | FileCheck %s --check-prefix INT64
 // RUN: fir-opt --split-input-file --fir-to-llvm-ir="target=aarch64-unknown-linux-gnu" %s | FileCheck %s --check-prefixes INT64
 // RUN: fir-opt --split-input-file --fir-to-llvm-ir="target=i386-unknown-linux-gnu" %s | FileCheck %s --check-prefixes INT32
-// RUN: fir-opt --split-input-file --fir-to-llvm-ir="target=powerpc64le-unknown-linux-gn" %s | FileCheck %s --check-prefixes INT64
+// RUN: fir-opt --split-input-file --fir-to-llvm-ir="target=powerpc64le-unknown-linux-gnu" %s | FileCheck %s --check-prefixes INT64
 
 //=============================================================================
 // SUMMARY: Tests for FIR --> LLVM MLIR conversion that *depend* on the target
diff --git a/flang/test/Fir/target-rewrite-integer.fir b/flang/test/Fir/target-rewrite-integer.fir
index 3be76e21a420..4cb2026cf9ee 100644
--- a/flang/test/Fir/target-rewrite-integer.fir
+++ b/flang/test/Fir/target-rewrite-integer.fir
@@ -1,6 +1,8 @@
 // RUN: fir-opt --split-input-file --target-rewrite="target=i386-unknown-linux-gnu" %s | FileCheck %s --check-prefixes=I32,ALL
 // RUN: fir-opt --split-input-file --target-rewrite="target=x86_64-unknown-linux-gnu" %s | FileCheck %s --check-prefixes=X64,ALL
+// RUN: fir-opt --split-input-file --target-rewrite="target=x86_64-apple-darwin" %s | FileCheck %s --check-prefixes=X64,ALL
 // RUN: fir-opt --split-input-file --target-rewrite="target=aarch64-unknown-linux-gnu" %s | FileCheck %s --check-prefixes=AARCH64,ALL
+// RUN: fir-opt --split-input-file --target-rewrite="target=aarch64-apple-darwin" %s | FileCheck %s --check-prefixes=AARCH64DARWIN,ALL
 // RUN: fir-opt --split-input-file --target-rewrite="target=powerpc64le-unknown-linux-gnu" %s | FileCheck %s --check-prefixes=PPC,ALL
 // RUN: fir-opt --split-input-file --target-rewrite="target=sparc64-unknown-linux-gnu" %s | FileCheck %s --check-prefixes=SPARCV9,ALL
 // RUN: fir-opt --split-input-file --target-rewrite="target=sparcv9-sun-solaris2.11" %s | FileCheck %s --check-prefixes=SPARCV9,ALL
@@ -17,6 +19,7 @@
 // I32: func.func{{.*}}@_FortranAioOutputLogical({{.*}}i1 {llvm.zeroext}) -> (i1 {llvm.zeroext})
 // X64: func.func{{.*}}@_FortranAioOutputLogical({{.*}}i1 {llvm.zeroext}) -> (i1 {llvm.zeroext})
 // AARCH64: func.func{{.*}}@_FortranAioOutputLogical({{.*}}i1 {llvm.zeroext}) -> (i1 {llvm.zeroext})
+// AARCH64DARWIN: func.func{{.*}}@_FortranAioOutputLogical({{.*}}i1 {llvm.zeroext}) -> (i1 {llvm.zeroext})
 // PPC: func.func{{.*}}@_FortranAioOutputLogical({{.*}}i1 {llvm.zeroext}) -> (i1 {llvm.zeroext})
 // SPARCV9: func.func{{.*}}@_FortranAioOutputLogical({{.*}}i1 {llvm.zeroext}) -> (i1 {llvm.zeroext})
 // LOONGARCH64: func.func{{.*}}@_FortranAioOutputLogical({{.*}}i1 {llvm.zeroext}) -> (i1 {llvm.zeroext})
@@ -49,6 +52,7 @@ func.func private @_FortranAioEndIoStatement(!fir.ref<i8>) -> i32 attributes {fi
 // I32: func.func{{.*}}@_SomeFunc_si1(si1 {llvm.signext}) -> (si1 {llvm.signext})
 // X64: func.func{{.*}}@_SomeFunc_si1(si1 {llvm.signext}) -> (si1 {llvm.signext})
 // AARCH64: func.func{{.*}}@_SomeFunc_si1(si1 {llvm.signext}) -> (si1 {llvm.signext})
+// AARCH64DARWIN: func.func{{.*}}@_SomeFunc_si1(si1 {llvm.signext}) -> (si1 {llvm.signext})
 // PPC: func.func{{.*}}@_SomeFunc_si1(si1 {llvm.signext}) -> (si1 {llvm.signext})
 // SPARCV9: func.func{{.*}}@_SomeFunc_si1(si1 {llvm.signext}) -> (si1 {llvm.signext})
 // LOONGARCH64: func.func{{.*}}@_SomeFunc_si1(si1 {llvm.signext}) -> (si1 {llvm.signext})
@@ -69,6 +73,7 @@ func.func private @_SomeFunc_si1(si1) -> si1 attributes {fir.runtime}
 // I32: func.func{{.*}}@_SomeFunc_ui1(ui1 {llvm.zeroext}) -> (ui1 {llvm.zeroext})
 // X64: func.func{{.*}}@_SomeFunc_ui1(ui1 {llvm.zeroext}) -> (ui1 {llvm.zeroext})
 // AARCH64: func.func{{.*}}@_SomeFunc_ui1(ui1 {llvm.zeroext}) -> (ui1 {llvm.zeroext})
+// AARCH64DARWIN: func.func{{.*}}@_SomeFunc_ui1(ui1 {llvm.zeroext}) -> (ui1 {llvm.zeroext})
 // PPC: func.func{{.*}}@_SomeFunc_ui1(ui1 {llvm.zeroext}) -> (ui1 {llvm.zeroext})
 // SPARCV9: func.func{{.*}}@_SomeFunc_ui1(ui1 {llvm.zeroext}) -> (ui1 {llvm.zeroext})
 // LOONGARCH64: func.func{{.*}}@_SomeFunc_ui1(ui1 {llvm.zeroext}) -> (ui1 {llvm.zeroext})
@@ -99,8 +104,20 @@ func.func private @_SomeFunc_ui1(ui1) -> ui1 attributes {fir.runtime}
 // end subroutine test
 
 // ALL-LABEL: @_QPtest_bindc
-// ALL: func.func private @cfun8(i8 {llvm.signext}) -> (i8 {llvm.signext}) attributes {fir.bindc_name = "cfun8"}
-// ALL: func.func private @cfun16(i16 {llvm.signext}) -> (i16 {llvm.signext}) attributes {fir.bindc_name = "cfun16"}
+// I32: func.func private @cfun8(i8 {llvm.signext}) -> (i8 {llvm.signext}) attributes {fir.bindc_name = "cfun8"}
+// I32: func.func private @cfun16(i16 {llvm.signext}) -> (i16 {llvm.signext}) attributes {fir.bindc_name = "cfun16"}
+// X64: func.func private @cfun8(i8 {llvm.signext}) -> (i8 {llvm.signext}) attributes {fir.bindc_name = "cfun8"}
+// X64: func.func private @cfun16(i16 {llvm.signext}) -> (i16 {llvm.signext}) attributes {fir.bindc_name = "cfun16"}
+// AARCH64: func.func private @cfun8(i8) -> i8 attributes {fir.bindc_name = "cfun8"}
+// AARCH64: func.func private @cfun16(i16) -> i16 attributes {fir.bindc_name = "cfun16"}
+// AARCH64DARWIN: func.func private @cfun8(i8 {llvm.signext}) -> (i8 {llvm.signext}) attributes {fir.bindc_name = "cfun8"}
+// AARCH64DARWIN: func.func private @cfun16(i16 {llvm.signext}) -> (i16 {llvm.signext}) attributes {fir.bindc_name = "cfun16"}
+// PPC: func.func private @cfun8(i8 {llvm.signext}) -> (i8 {llvm.signext}) attributes {fir.bindc_name = "cfun8"}
+// PPC: func.func private @cfun16(i16 {llvm.signext}) -> (i16 {llvm.signext}) attributes {fir.bindc_name = "cfun16"}
+// SPARCV9: func.func private @cfun8(i8 {llvm.signext}) -> (i8 {llvm.signext}) attributes {fir.bindc_name = "cfun8"}
+// SPARCV9: func.func private @cfun16(i16 {llvm.signext}) -> (i16 {llvm.signext}) attributes {fir.bindc_name = "cfun16"}
+// LOONGARCH64: func.func private @cfun8(i8 {llvm.signext}) -> (i8 {llvm.signext}) attributes {fir.bindc_name = "cfun8"}
+// LOONGARCH64: func.func private @cfun16(i16 {llvm.signext}) -> (i16 {llvm.signext}) attributes {fir.bindc_name = "cfun16"}
 func.func @_QPtest_bindc(%arg0: !fir.ref<i8> {fir.bindc_name = "x"}, %arg1: !fir.ref<i16> {fir.bindc_name = "y"}) {
   %0 = fir.load %arg0 : !fir.ref<i8>
   %1 = fir.call @cfun8(%0) fastmath<contract> : (i8) -> i8