diff --git a/llvm/docs/ReleaseNotes.rst b/llvm/docs/ReleaseNotes.rst
--- a/llvm/docs/ReleaseNotes.rst
+++ b/llvm/docs/ReleaseNotes.rst
@@ -156,6 +156,9 @@
 Changes to the C API
 --------------------
 
+* Add `LLVMGetCastOpcode` function to aid users of `LLVMBuildCast` resolve the
+  best cast operation given a source value and destination type.
+  This function is a direct wrapper of `CastInst::getCastOpcode`.
 
 Changes to the Go bindings
 --------------------------
diff --git a/llvm/include/llvm-c/Core.h b/llvm/include/llvm-c/Core.h
--- a/llvm/include/llvm-c/Core.h
+++ b/llvm/include/llvm-c/Core.h
@@ -3892,6 +3892,9 @@
 LLVMValueRef LLVMBuildIntCast(LLVMBuilderRef, LLVMValueRef Val, /*Signed cast!*/
                               LLVMTypeRef DestTy, const char *Name);
 
+LLVMOpcode LLVMGetCastOpcode(LLVMValueRef Src, LLVMBool SrcIsSigned,
+                             LLVMTypeRef DestTy, LLVMBool DestIsSigned);
+
 /* Comparisons */
 LLVMValueRef LLVMBuildICmp(LLVMBuilderRef, LLVMIntPredicate Op,
                            LLVMValueRef LHS, LLVMValueRef RHS,
diff --git a/llvm/lib/IR/Core.cpp b/llvm/lib/IR/Core.cpp
--- a/llvm/lib/IR/Core.cpp
+++ b/llvm/lib/IR/Core.cpp
@@ -3837,6 +3837,12 @@
   return wrap(unwrap(B)->CreateFPCast(unwrap(Val), unwrap(DestTy), Name));
 }
 
+LLVMOpcode LLVMGetCastOpcode(LLVMValueRef Src, LLVMBool SrcIsSigned,
+                             LLVMTypeRef DestTy, LLVMBool DestIsSigned) {
+  return map_to_llvmopcode(CastInst::getCastOpcode(
+      unwrap(Src), SrcIsSigned, unwrap(DestTy), DestIsSigned));
+}
+
 /*--.. Comparisons .........................................................--*/
 
 LLVMValueRef LLVMBuildICmp(LLVMBuilderRef B, LLVMIntPredicate Op,