diff --git a/clang/lib/Basic/Targets/RISCV.h b/clang/lib/Basic/Targets/RISCV.h
--- a/clang/lib/Basic/Targets/RISCV.h
+++ b/clang/lib/Basic/Targets/RISCV.h
@@ -96,7 +96,19 @@
                             DiagnosticsEngine &Diags) override;
 
   bool hasExtIntType() const override { return true; }
+
+  CallingConvCheckResult checkCallingConvention(CallingConv CC) const override {
+    switch (CC) {
+    case CC_Swift:
+      return CCCR_OK;
+    case CC_SwiftAsync:
+      return CCCR_Error;
+    default:
+      return CCCR_Warning;
+    }
+  }
 };
+
 class LLVM_LIBRARY_VISIBILITY RISCV32TargetInfo : public RISCVTargetInfo {
 public:
   RISCV32TargetInfo(const llvm::Triple &Triple, const TargetOptions &Opts)
diff --git a/clang/lib/CodeGen/TargetInfo.cpp b/clang/lib/CodeGen/TargetInfo.cpp
--- a/clang/lib/CodeGen/TargetInfo.cpp
+++ b/clang/lib/CodeGen/TargetInfo.cpp
@@ -10552,8 +10552,9 @@
 //===----------------------------------------------------------------------===//
 
 namespace {
-class RISCVABIInfo : public DefaultABIInfo {
+class RISCVABIInfo : public SwiftABIInfo {
 private:
+  DefaultABIInfo defaultInfo;
   // Size of the integer ('x') registers in bits.
   unsigned XLen;
   // Size of the floating point ('f') registers in bits. Note that the target
@@ -10570,7 +10571,7 @@
 
 public:
   RISCVABIInfo(CodeGen::CodeGenTypes &CGT, unsigned XLen, unsigned FLen)
-      : DefaultABIInfo(CGT), XLen(XLen), FLen(FLen) {}
+      : SwiftABIInfo(CGT), defaultInfo(CGT), XLen(XLen), FLen(FLen) {}
 
   // DefaultABIInfo's classifyReturnType and classifyArgumentType are
   // non-virtual, but computeInfo is virtual, so we overload it.
@@ -10593,6 +10594,14 @@
                                                CharUnits Field1Off,
                                                llvm::Type *Field2Ty,
                                                CharUnits Field2Off) const;
+
+private:
+  bool shouldPassIndirectlyForSwift(ArrayRef<llvm::Type *> scalars,
+                                    bool asReturnValue) const override {
+    return occupiesMoreThan(CGT, scalars, /*total*/ 4);
+  }
+
+  bool isSwiftErrorInRegister() const override { return false; }
 };
 } // end anonymous namespace
 
diff --git a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
--- a/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
+++ b/llvm/lib/Target/RISCV/RISCVISelLowering.cpp
@@ -8443,6 +8443,8 @@
   default:
     report_fatal_error("Unsupported calling convention");
   case CallingConv::C:
+  case CallingConv::Swift:
+  case CallingConv::SwiftTail:
   case CallingConv::Fast:
     break;
   case CallingConv::GHC: