diff --git a/llvm/include/llvm/Analysis/VectorUtils.h b/llvm/include/llvm/Analysis/VectorUtils.h
--- a/llvm/include/llvm/Analysis/VectorUtils.h
+++ b/llvm/include/llvm/Analysis/VectorUtils.h
@@ -48,7 +48,9 @@
   AVX,          // x86 AVX
   AVX2,         // x86 AVX2
   AVX512,       // x86 AVX512
-  Unknown       // Unknown ISA
+  LLVM,         // LLVM internal ISA for functions that are not
+  // attached to an existing ABI via name mangling.
+  Unknown // Unknown ISA
 };
 
 /// Encapsulates information needed to describe a parameter.
@@ -103,6 +105,9 @@
 };
 
 namespace VFABI {
+/// LLVM Internal VFABI ISA token for Vector Functions (VF).
+static constexpr char const *_LLVM_ = "_LLVM_";
+
 /// Function to contruct a VFInfo out of a mangled names in the
 /// following format:
 ///
diff --git a/llvm/lib/Analysis/VFABIDemangling.cpp b/llvm/lib/Analysis/VFABIDemangling.cpp
--- a/llvm/lib/Analysis/VFABIDemangling.cpp
+++ b/llvm/lib/Analysis/VFABIDemangling.cpp
@@ -28,15 +28,20 @@
   if (MangledName.empty())
     return ParseRet::Error;
 
-  ISA = StringSwitch<VFISAKind>(MangledName.take_front(1))
-            .Case("n", VFISAKind::AdvancedSIMD)
-            .Case("s", VFISAKind::SVE)
-            .Case("b", VFISAKind::SSE)
-            .Case("c", VFISAKind::AVX)
-            .Case("d", VFISAKind::AVX2)
-            .Case("e", VFISAKind::AVX512)
-            .Default(VFISAKind::Unknown);
-  MangledName = MangledName.drop_front(1);
+  if (MangledName.startswith(VFABI::_LLVM_)) {
+    MangledName = MangledName.drop_front(strlen(VFABI::_LLVM_));
+    ISA = VFISAKind::LLVM;
+  } else {
+    ISA = StringSwitch<VFISAKind>(MangledName.take_front(1))
+              .Case("n", VFISAKind::AdvancedSIMD)
+              .Case("s", VFISAKind::SVE)
+              .Case("b", VFISAKind::SSE)
+              .Case("c", VFISAKind::AVX)
+              .Case("d", VFISAKind::AVX2)
+              .Case("e", VFISAKind::AVX512)
+              .Default(VFISAKind::Unknown);
+    MangledName = MangledName.drop_front(1);
+  }
 
   return ParseRet::OK;
 }
@@ -287,6 +292,7 @@
 // Format of the ABI name:
 // _ZGV<isa><mask><vlen><parameters>_<scalarname>[(<redirection>)]
 Optional<VFInfo> VFABI::tryDemangleForVFABI(StringRef MangledName) {
+  const StringRef OriginalName = MangledName;
   // Assume there is no custom name <redirection>, and therefore the
   // vector name consists of
   // _ZGV<isa><mask><vlen><parameters>_<scalarname>.
@@ -370,6 +376,11 @@
       return None;
   }
 
+  // LLVM internal mapping via the TargetLibraryInfo (TLI) must be
+  // redirected to an existing name.
+  if (ISA == VFISAKind::LLVM && VectorName == OriginalName)
+    return None;
+
   // When <mask> is "M", we need to add a parameter that is used as
   // global predicate for the function.
   if (IsMasked) {
diff --git a/llvm/unittests/Analysis/VectorFunctionABITest.cpp b/llvm/unittests/Analysis/VectorFunctionABITest.cpp
--- a/llvm/unittests/Analysis/VectorFunctionABITest.cpp
+++ b/llvm/unittests/Analysis/VectorFunctionABITest.cpp
@@ -346,6 +346,13 @@
   __COMMON_CHECKS;
   EXPECT_EQ(VectorName, "_ZGVeN2vls2Ls27Us4Rs5l1L10U100R1000u2_sin");
 
+  // LLVM_VF: <isa> = LLVM internal vector function.
+  EXPECT_TRUE(
+      invokeParser("_ZGV_LLVM_N2vls2Ls27Us4Rs5l1L10U100R1000u2_sin(vectorf)"));
+  EXPECT_EQ(ISA, VFISAKind::LLVM);
+  __COMMON_CHECKS;
+  EXPECT_EQ(VectorName, "vectorf");
+
   // Unknown ISA (randomly using "q"). This test will need update if
   // some targets decide to use "q" as their ISA token.
   EXPECT_TRUE(invokeParser("_ZGVqN2vls2Ls27Us4Rs5l1L10U100R1000u2_sin"));
@@ -473,3 +480,9 @@
   Exp.push_back("_ZGVnN4v_g");
   EXPECT_EQ(Mappings, Exp);
 }
+
+TEST_F(VFABIParserTest, LLVM_InternalISA) {
+  EXPECT_FALSE(invokeParser("_ZGV_LLVM_N2v_sin"));
+  EXPECT_TRUE(invokeParser("_ZGV_LLVM_N2v_sin_(vector_name)"));
+  EXPECT_EQ(ISA, VFISAKind::LLVM);
+}