Index: clang/include/clang/AST/Decl.h
===================================================================
--- clang/include/clang/AST/Decl.h
+++ clang/include/clang/AST/Decl.h
@@ -2327,6 +2327,10 @@
   /// limited representation in the AST.
   SourceRange getReturnTypeSourceRange() const;
 
+  /// Attempt to compute an informative source range covering the
+  /// function parameters. This omits the ellipsis of a variadic function.
+  SourceRange getParametersSourceRange() const;
+
   /// Get the declared return type, which may differ from the actual return
   /// type if the return type is deduced.
   QualType getDeclaredReturnType() const {
Index: clang/lib/AST/Decl.cpp
===================================================================
--- clang/lib/AST/Decl.cpp
+++ clang/lib/AST/Decl.cpp
@@ -3301,6 +3301,17 @@
   return RTRange;
 }
 
+SourceRange FunctionDecl::getParametersSourceRange() const {
+  auto NP = getNumParams();
+  if (NP == 0)
+    return SourceRange();
+
+  auto Begin = ParamInfo[0]->getSourceRange().getBegin();
+  auto End = ParamInfo[NP - 1]->getSourceRange().getEnd();
+
+  return SourceRange(Begin, End);
+}
+
 SourceRange FunctionDecl::getExceptionSpecSourceRange() const {
   const TypeSourceInfo *TSI = getTypeSourceInfo();
   if (!TSI)
Index: clang/unittests/AST/SourceLocationTest.cpp
===================================================================
--- clang/unittests/AST/SourceLocationTest.cpp
+++ clang/unittests/AST/SourceLocationTest.cpp
@@ -648,6 +648,32 @@
       Language::Lang_CXX11));
 }
 
+class FunctionDeclParametersRangeVerifier : public RangeVerifier<FunctionDecl> {
+protected:
+  SourceRange getRange(const FunctionDecl &Function) override {
+    return Function.getParametersSourceRange();
+  }
+};
+
+TEST(FunctionDeclParameters, FunctionDeclSingleParameter) {
+  FunctionDeclParametersRangeVerifier Verifier;
+  Verifier.expectRange(1, 8, 1, 12);
+  EXPECT_TRUE(Verifier.match("void f(int a);\n", functionDecl()));
+}
+
+TEST(FunctionDeclParameters, FunctionDeclMultipleParameters) {
+  FunctionDeclParametersRangeVerifier Verifier;
+  Verifier.expectRange(1, 8, 1, 28);
+  EXPECT_TRUE(
+      Verifier.match("void f(int a, int b, char *c);\n", functionDecl()));
+}
+
+TEST(FunctionDeclParameters, FunctionDeclWithDefaultValue) {
+  FunctionDeclParametersRangeVerifier Verifier;
+  Verifier.expectRange(1, 8, 1, 16);
+  EXPECT_TRUE(Verifier.match("void f(int a = 5);\n", functionDecl()));
+}
+
 TEST(CXXMethodDecl, CXXMethodDeclWithThrowSpecification) {
   RangeVerifier<FunctionDecl> Verifier;
   Verifier.expectRange(2, 1, 2, 16);