diff --git a/include/swift/SIL/ApplySite.h b/include/swift/SIL/ApplySite.h
index de97fef3e9bf0..e11ca87b047b6 100644
--- a/include/swift/SIL/ApplySite.h
+++ b/include/swift/SIL/ApplySite.h
@@ -21,6 +21,7 @@
 #ifndef SWIFT_SIL_APPLYSITE_H
 #define SWIFT_SIL_APPLYSITE_H
 
+#include "swift/Basic/STLExtras.h"
 #include "swift/SIL/SILArgument.h"
 #include "swift/SIL/SILBasicBlock.h"
 #include "swift/SIL/SILFunction.h"
@@ -29,6 +30,8 @@
 
 namespace swift {
 
+class FullApplySite;
+
 //===----------------------------------------------------------------------===//
 //                                 ApplySite
 //===----------------------------------------------------------------------===//
@@ -396,6 +399,10 @@ class ApplySite {
     llvm_unreachable("covered switch");
   }
 
+  /// Returns true if \p op is an operand that passes an indirect
+  /// result argument to the apply site.
+  bool isIndirectResultOperand(const Operand &op) const;
+
   /// Return whether the given apply is of a formally-throwing function
   /// which is statically known not to throw.
   bool isNonThrowing() const {
@@ -425,6 +432,10 @@ class ApplySite {
   }
 
   void dump() const LLVM_ATTRIBUTE_USED { getInstruction()->dump(); }
+
+  /// Attempt to cast this apply site to a full apply site, returning None on
+  /// failure.
+  Optional<FullApplySite> asFullApplySite() const;
 };
 
 //===----------------------------------------------------------------------===//
@@ -562,12 +573,6 @@ class FullApplySite : public ApplySite {
     return op.getOperandNumber() < getOperandIndexOfFirstArgument();
   }
 
-  /// Returns true if \p op is an operand that passes an indirect
-  /// result argument to the apply site.
-  bool isIndirectResultOperand(const Operand &op) const {
-    return getCalleeArgIndex(op) < getNumIndirectSILResults();
-  }
-
   /// Is this an ApplySite that begins the evaluation of a coroutine.
   bool beginsCoroutineEvaluation() const {
     switch (getKind()) {
@@ -637,6 +642,12 @@ class FullApplySite : public ApplySite {
     llvm_unreachable("covered switch isn't covered");
   }
 
+  /// Returns true if \p op is an operand that passes an indirect
+  /// result argument to the apply site.
+  bool isIndirectResultOperand(const Operand &op) const {
+    return getCalleeArgIndex(op) < getNumIndirectSILResults();
+  }
+
   static FullApplySite getFromOpaqueValue(void *p) { return FullApplySite(p); }
 
   static bool classof(const SILInstruction *inst) {
@@ -729,4 +740,23 @@ template <> struct DenseMapInfo<::swift::FullApplySite> {
 
 } // namespace llvm
 
+//===----------------------------------------------------------------------===//
+//           Inline Definitions to work around Forward Declaration
+//===----------------------------------------------------------------------===//
+
+namespace swift {
+
+inline Optional<FullApplySite> ApplySite::asFullApplySite() const {
+  return FullApplySite::isa(getInstruction());
+}
+
+inline bool ApplySite::isIndirectResultOperand(const Operand &op) const {
+  auto fas = asFullApplySite();
+  if (!fas)
+    return false;
+  return fas->isIndirectResultOperand(op);
+}
+
+} // namespace swift
+
 #endif