diff --git a/clang/include/clang-c/Index.h b/clang/include/clang-c/Index.h
--- a/clang/include/clang-c/Index.h
+++ b/clang/include/clang-c/Index.h
@@ -2789,7 +2789,9 @@
 
   CXType_ExtVector = 176,
   CXType_Atomic = 177,
-  CXType_BTFTagAttributed = 178
+  CXType_BTFTagAttributed = 178,
+  /* Represents a type that as been substituted for a template type parameter */
+  CXType_SubstTemplateTypeParm = 179
 };
 
 /**
@@ -3447,6 +3449,13 @@
  */
 CINDEX_LINKAGE CXType clang_Type_getValueType(CXType CT);
 
+/**
+ * Gets the replacement type for a SubstTemplateTypeParm type.
+ *
+ * If any other type kind is passed in, an invalid type is returned.
+ */
+CINDEX_LINKAGE CXType clang_Type_getReplacementType(CXType CT);
+
 /**
  * Return the offset of the field represented by the Cursor.
  *
diff --git a/clang/test/Index/print-type.cpp b/clang/test/Index/print-type.cpp
--- a/clang/test/Index/print-type.cpp
+++ b/clang/test/Index/print-type.cpp
@@ -171,7 +171,7 @@
 // CHECK: VarDecl=autoI:54:6 (Definition) [type=int] [typekind=Auto] [canonicaltype=int] [canonicaltypekind=Int] [isPOD=1]
 // CHECK: IntegerLiteral= [type=int] [typekind=Int] [isPOD=1]
 // CHECK: VarDecl=autoTbar:55:6 (Definition) [type=int] [typekind=Auto] [canonicaltype=int] [canonicaltypekind=Int] [isPOD=1]
-// CHECK: CallExpr=tbar:36:3 [type=int] [typekind=Unexposed] [canonicaltype=int] [canonicaltypekind=Int] [args= [int] [Int]] [isPOD=1]
+// CHECK: CallExpr=tbar:36:3 [type=int] [typekind=SubstTemplateTypeParm] [canonicaltype=int] [canonicaltypekind=Int] [args= [int] [Int]] [isPOD=1]
 // CHECK: UnexposedExpr=tbar:36:3 [type=int (*)(int)] [typekind=Pointer] [canonicaltype=int (*)(int)] [canonicaltypekind=Pointer] [isPOD=1] [pointeetype=int (int)] [pointeekind=FunctionProto]
 // CHECK: DeclRefExpr=tbar:36:3 RefName=[55:17 - 55:21] RefName=[55:21 - 55:26] [type=int (int)] [typekind=FunctionProto] [canonicaltype=int (int)] [canonicaltypekind=FunctionProto] [isPOD=0]
 // CHECK: IntegerLiteral= [type=int] [typekind=Int] [isPOD=1]
diff --git a/clang/tools/libclang/CXType.cpp b/clang/tools/libclang/CXType.cpp
--- a/clang/tools/libclang/CXType.cpp
+++ b/clang/tools/libclang/CXType.cpp
@@ -118,12 +118,17 @@
     TKCASE(Attributed);
     TKCASE(BTFTagAttributed);
     TKCASE(Atomic);
+    TKCASE(SubstTemplateTypeParm);
     default:
       return CXType_Unexposed;
   }
 #undef TKCASE
 }
 
+static CXTypeKind GetSubstTemplateTypeParmTypeKind(const SubstTemplateTypeParmType* TP) {
+  const QualType RT = TP->getReplacementType();
+  return GetTypeKind(RT);
+}
 
 CXType cxtype::MakeCXType(QualType T, CXTranslationUnit TU) {
   CXTypeKind TK = CXType_Invalid;
@@ -635,6 +640,7 @@
     TKIND(OCLQueue);
     TKIND(OCLReserveID);
     TKIND(Atomic);
+    TKIND(SubstTemplateTypeParm);
   }
 #undef TKIND
   return cxstring::createRef(s);
@@ -1355,3 +1361,13 @@
   const auto *AT = T->castAs<AtomicType>();
   return MakeCXType(AT->getValueType(), GetTU(CT));
 }
+
+CXType clang_Type_getReplacementType(CXType CT) {
+  QualType T = GetQualType(CT);
+
+  if (T.isNull() || T->getTypeClass() != Type::SubstTemplateTypeParm)
+    return MakeCXType(QualType(), GetTU(CT));
+
+  const auto *ST = T->castAs<SubstTemplateTypeParmType>();
+  return MakeCXType(ST->getReplacementType(), GetTU(CT));
+}
\ No newline at end of file
diff --git a/clang/tools/libclang/libclang.map b/clang/tools/libclang/libclang.map
--- a/clang/tools/libclang/libclang.map
+++ b/clang/tools/libclang/libclang.map
@@ -167,6 +167,7 @@
     clang_Type_getSizeOf;
     clang_Type_getTemplateArgumentAsType;
     clang_Type_getValueType;
+    clang_Type_getReplacementType;
     clang_Type_isTransparentTagTypedef;
     clang_Type_visitFields;
     clang_VerbatimBlockLineComment_getText;