diff --git a/clang/include/clang/Basic/Cuda.h b/clang/include/clang/Basic/Cuda.h
--- a/clang/include/clang/Basic/Cuda.h
+++ b/clang/include/clang/Basic/Cuda.h
@@ -33,8 +33,10 @@
   CUDA_112,
   CUDA_113,
   CUDA_114,
-  LATEST = CUDA_114,
-  LATEST_SUPPORTED = CUDA_101,
+  FULLY_SUPPORTED = CUDA_101,
+  PARTIALLY_SUPPORTED =
+      CUDA_114, // Partially supported. Proceed with a warning.
+  NEW = 10000,  // Too new. Issue a warning, but allow using it.
 };
 const char *CudaVersionToString(CudaVersion V);
 // Input is "Major.Minor"
diff --git a/clang/include/clang/Basic/DiagnosticDriverKinds.td b/clang/include/clang/Basic/DiagnosticDriverKinds.td
--- a/clang/include/clang/Basic/DiagnosticDriverKinds.td
+++ b/clang/include/clang/Basic/DiagnosticDriverKinds.td
@@ -77,8 +77,11 @@
   "but installation at %3 is %4; use '--cuda-path' to specify a different CUDA "
   "install, pass a different GPU arch with '--cuda-gpu-arch', or pass "
   "'--no-cuda-version-check'">;
-def warn_drv_unknown_cuda_version: Warning<
-  "unknown CUDA version: %0; assuming the latest supported version %1">,
+def warn_drv_new_cuda_version: Warning<
+  "CUDA version %0 is newer than the latest%select{| partially}1 supported version %2">,
+  InGroup<CudaUnknownVersion>;
+def warn_drv_partially_supported_cuda_version: Warning<
+  "CUDA version %0 is only partially supported">,
   InGroup<CudaUnknownVersion>;
 def err_drv_cuda_host_arch : Error<
   "unsupported architecture '%0' for host compilation">;
diff --git a/clang/lib/Basic/Cuda.cpp b/clang/lib/Basic/Cuda.cpp
--- a/clang/lib/Basic/Cuda.cpp
+++ b/clang/lib/Basic/Cuda.cpp
@@ -40,6 +40,8 @@
     return "11.3";
   case CudaVersion::CUDA_114:
     return "11.4";
+  case CudaVersion::NEW:
+    return "[new]";
   }
   llvm_unreachable("invalid enum");
 }
@@ -192,7 +194,7 @@
 CudaVersion MaxVersionForCudaArch(CudaArch A) {
   // AMD GPUs do not depend on CUDA versions.
   if (IsAMDGpuArch(A))
-    return CudaVersion::LATEST;
+    return CudaVersion::NEW;
 
   switch (A) {
   case CudaArch::UNKNOWN:
@@ -203,7 +205,7 @@
   case CudaArch::SM_30:
     return CudaVersion::CUDA_110;
   default:
-    return CudaVersion::LATEST;
+    return CudaVersion::NEW;
   }
 }
 
diff --git a/clang/lib/Driver/ToolChains/Cuda.h b/clang/lib/Driver/ToolChains/Cuda.h
--- a/clang/lib/Driver/ToolChains/Cuda.h
+++ b/clang/lib/Driver/ToolChains/Cuda.h
@@ -31,7 +31,8 @@
   bool IsValid = false;
   CudaVersion Version = CudaVersion::UNKNOWN;
   std::string DetectedVersion;
-  bool DetectedVersionIsNotSupported = false;
+  bool DetectedVersionIsPartiallySupported = false;
+  bool DetectedVersionIsTooNew = false;
   std::string InstallPath;
   std::string BinPath;
   std::string LibPath;
@@ -62,7 +63,10 @@
   void print(raw_ostream &OS) const;
 
   /// Get the detected Cuda install's version.
-  CudaVersion version() const { return Version; }
+  CudaVersion version() const {
+    return Version == CudaVersion::NEW ? CudaVersion::PARTIALLY_SUPPORTED
+                                       : Version;
+  }
   /// Get the detected Cuda installation path.
   StringRef getInstallPath() const { return InstallPath; }
   /// Get the detected path to Cuda's bin directory.
diff --git a/clang/lib/Driver/ToolChains/Cuda.cpp b/clang/lib/Driver/ToolChains/Cuda.cpp
--- a/clang/lib/Driver/ToolChains/Cuda.cpp
+++ b/clang/lib/Driver/ToolChains/Cuda.cpp
@@ -17,6 +17,7 @@
 #include "clang/Driver/InputInfo.h"
 #include "clang/Driver/Options.h"
 #include "llvm/ADT/Optional.h"
+#include "llvm/ADT/StringExtras.h"
 #include "llvm/Option/ArgList.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Host.h"
@@ -35,24 +36,9 @@
 
 namespace {
 struct CudaVersionInfo {
-  std::string DetectedVersion;
+  std::string DetectedVersionString;
   CudaVersion Version;
 };
-// Parses the contents of version.txt in an CUDA installation.  It should
-// contain one line of the from e.g. "CUDA Version 7.5.2".
-CudaVersionInfo parseCudaVersionFile(llvm::StringRef V) {
-  V = V.trim();
-  if (!V.startswith("CUDA Version "))
-    return {V.str(), CudaVersion::UNKNOWN};
-  V = V.substr(strlen("CUDA Version "));
-  SmallVector<StringRef,4> VersionParts;
-  V.split(VersionParts, '.');
-  return {"version.txt: " + V.str() + ".",
-          VersionParts.size() < 2
-              ? CudaVersion::UNKNOWN
-              : CudaStringToVersion(
-                    join_items(".", VersionParts[0], VersionParts[1]))};
-}
 
 CudaVersion getCudaVersion(uint32_t raw_version) {
   if (raw_version < 7050)
@@ -83,7 +69,7 @@
     return CudaVersion::CUDA_113;
   if (raw_version < 11050)
     return CudaVersion::CUDA_114;
-  return CudaVersion::LATEST;
+  return CudaVersion::NEW;
 }
 
 CudaVersionInfo parseCudaHFile(llvm::StringRef Input) {
@@ -106,21 +92,23 @@
             StartsWithWords(Input.ltrim(), {"#", "define", "CUDA_VERSION"})) {
       uint32_t RawVersion;
       Line->consumeInteger(10, RawVersion);
-      return {"cuda.h: CUDA_VERSION=" + Twine(RawVersion).str() + ".",
-              getCudaVersion(RawVersion)};
+      return {llvm::utostr(RawVersion), getCudaVersion(RawVersion)};
     }
     // Find next non-empty line.
     Input = Input.drop_front(Input.find_first_of("\n\r")).ltrim();
   }
-  return {"cuda.h: CUDA_VERSION not found.", CudaVersion::UNKNOWN};
+  return {"CUDA_VERSION not found.", CudaVersion::UNKNOWN};
 }
 } // namespace
 
 void CudaInstallationDetector::WarnIfUnsupportedVersion() {
-  if (DetectedVersionIsNotSupported)
-    D.Diag(diag::warn_drv_unknown_cuda_version)
+  if (DetectedVersionIsTooNew)
+    D.Diag(diag::warn_drv_new_cuda_version)
         << DetectedVersion
-        << CudaVersionToString(CudaVersion::LATEST_SUPPORTED);
+        << (CudaVersion::PARTIALLY_SUPPORTED != CudaVersion::FULLY_SUPPORTED)
+        << CudaVersionToString(CudaVersion::PARTIALLY_SUPPORTED);
+  else if (DetectedVersionIsPartiallySupported)
+    D.Diag(diag::warn_drv_partially_supported_cuda_version) << DetectedVersion;
 }
 
 CudaInstallationDetector::CudaInstallationDetector(
@@ -213,28 +201,23 @@
       continue;
 
     CudaVersionInfo VersionInfo = {"", CudaVersion::UNKNOWN};
-    if (auto VersionFile = FS.getBufferForFile(InstallPath + "/version.txt"))
-      VersionInfo = parseCudaVersionFile((*VersionFile)->getBuffer());
-    // If version file didn't give us the version, try to find it in cuda.h
-    if (VersionInfo.Version == CudaVersion::UNKNOWN)
-      if (auto CudaHFile = FS.getBufferForFile(InstallPath + "/include/cuda.h"))
-        VersionInfo = parseCudaHFile((*CudaHFile)->getBuffer());
-    // As the last resort, make an educated guess between CUDA-7.0, (which had
-    // no version.txt file and had old-style libdevice bitcode ) and an unknown
-    // recent CUDA version (no version.txt, new style bitcode).
+    if (auto CudaHFile = FS.getBufferForFile(InstallPath + "/include/cuda.h"))
+      VersionInfo = parseCudaHFile((*CudaHFile)->getBuffer());
+    // As the last resort, make an educated guess between CUDA-7.0, which had
+    // old-style libdevice bitcode, and an unknown recent CUDA version.
     if (VersionInfo.Version == CudaVersion::UNKNOWN) {
-      VersionInfo.Version = (FS.exists(LibDevicePath + "/libdevice.10.bc"))
-                                ? Version = CudaVersion::LATEST
+      VersionInfo.Version = FS.exists(LibDevicePath + "/libdevice.10.bc")
+                                ? Version = CudaVersion::NEW
                                 : Version = CudaVersion::CUDA_70;
-      VersionInfo.DetectedVersion = "no version found in version.txt or cuda.h";
+      VersionInfo.DetectedVersionString = "[unknown]";
     }
 
     Version = VersionInfo.Version;
-    DetectedVersion = VersionInfo.DetectedVersion;
+    DetectedVersion = VersionInfo.DetectedVersionString;
 
-    // TODO(tra): remove the warning once we have all features of 10.2
-    // and 11.0 implemented.
-    DetectedVersionIsNotSupported = Version > CudaVersion::LATEST_SUPPORTED;
+    DetectedVersionIsPartiallySupported =
+        Version > CudaVersion::FULLY_SUPPORTED;
+    DetectedVersionIsTooNew = Version > CudaVersion::PARTIALLY_SUPPORTED;
 
     if (Version >= CudaVersion::CUDA_90) {
       // CUDA-9+ uses single libdevice file for all GPU variants.
diff --git a/clang/test/Driver/Inputs/CUDA-new/usr/local/cuda/bin/.keep b/clang/test/Driver/Inputs/CUDA-new/usr/local/cuda/bin/.keep
new file mode 100644
diff --git a/clang/test/Driver/Inputs/CUDA-new/usr/local/cuda/include/.keep b/clang/test/Driver/Inputs/CUDA-new/usr/local/cuda/include/.keep
new file mode 100644
diff --git a/clang/test/Driver/Inputs/CUDA-new/usr/local/cuda/include/cuda.h b/clang/test/Driver/Inputs/CUDA-new/usr/local/cuda/include/cuda.h
new file mode 100644
--- /dev/null
+++ b/clang/test/Driver/Inputs/CUDA-new/usr/local/cuda/include/cuda.h
@@ -0,0 +1,7 @@
+//
+// Placeholder file for testing CUDA version detection
+//
+
+#define CUDA_VERSION 99010
+
+//
diff --git a/clang/test/Driver/Inputs/CUDA-new/usr/local/cuda/lib/.keep b/clang/test/Driver/Inputs/CUDA-new/usr/local/cuda/lib/.keep
new file mode 100644
diff --git a/clang/test/Driver/Inputs/CUDA-new/usr/local/cuda/lib64/.keep b/clang/test/Driver/Inputs/CUDA-new/usr/local/cuda/lib64/.keep
new file mode 100644
diff --git a/clang/test/Driver/Inputs/CUDA-new/usr/local/cuda/nvvm/libdevice/libdevice.10.bc b/clang/test/Driver/Inputs/CUDA-new/usr/local/cuda/nvvm/libdevice/libdevice.10.bc
new file mode 100644
diff --git a/clang/test/Driver/Inputs/CUDA-unknown/usr/local/cuda/version.txt b/clang/test/Driver/Inputs/CUDA-unknown/usr/local/cuda/version.txt
deleted file mode 100644
--- a/clang/test/Driver/Inputs/CUDA-unknown/usr/local/cuda/version.txt
+++ /dev/null
@@ -1 +0,0 @@
-CUDA Version 999.999.999
diff --git a/clang/test/Driver/Inputs/CUDA_80/usr/local/cuda/include/cuda.h b/clang/test/Driver/Inputs/CUDA_80/usr/local/cuda/include/cuda.h
new file mode 100644
--- /dev/null
+++ b/clang/test/Driver/Inputs/CUDA_80/usr/local/cuda/include/cuda.h
@@ -0,0 +1,7 @@
+//
+// Placeholder file for testing CUDA version detection
+//
+
+#define CUDA_VERSION 8000
+
+//
diff --git a/clang/test/Driver/Inputs/CUDA_80/usr/local/cuda/version.txt b/clang/test/Driver/Inputs/CUDA_80/usr/local/cuda/version.txt
deleted file mode 100644
--- a/clang/test/Driver/Inputs/CUDA_80/usr/local/cuda/version.txt
+++ /dev/null
@@ -1 +0,0 @@
-CUDA Version 8.0.42
diff --git a/clang/test/Driver/Inputs/CUDA_90/usr/local/cuda/include/cuda.h b/clang/test/Driver/Inputs/CUDA_90/usr/local/cuda/include/cuda.h
new file mode 100644
--- /dev/null
+++ b/clang/test/Driver/Inputs/CUDA_90/usr/local/cuda/include/cuda.h
@@ -0,0 +1,7 @@
+//
+// Placeholder file for testing CUDA version detection
+//
+
+#define CUDA_VERSION 9000
+
+//
diff --git a/clang/test/Driver/cuda-version-check.cu b/clang/test/Driver/cuda-version-check.cu
--- a/clang/test/Driver/cuda-version-check.cu
+++ b/clang/test/Driver/cuda-version-check.cu
@@ -8,15 +8,12 @@
 // RUN:    FileCheck %s --check-prefix=OK
 // RUN: %clang --target=x86_64-linux -v -### --cuda-gpu-arch=sm_60 --cuda-path=%S/Inputs/CUDA_80/usr/local/cuda 2>&1 %s | \
 // RUN:    FileCheck %s --check-prefix=OK
-// Test version guess when no version.txt or cuda.h are found
+// Test version guess when cuda.h has not been found
 // RUN: %clang --target=x86_64-linux -v -### --cuda-gpu-arch=sm_60 --cuda-path=%S/Inputs/CUDA-unknown/usr/local/cuda 2>&1 %s | \
 // RUN:    FileCheck %s --check-prefix=UNKNOWN_VERSION
-// Unknown version with version.txt present
-// RUN: %clang --target=x86_64-linux -v -### --cuda-gpu-arch=sm_60 --cuda-path=%S/Inputs/CUDA_102/usr/local/cuda 2>&1 %s | \
-// RUN:    FileCheck %s --check-prefix=UNKNOWN_VERSION_V
-// Unknown version with no version.txt but with version info present in cuda.h
-// RUN: %clang --target=x86_64-linux -v -### --cuda-gpu-arch=sm_60 --cuda-path=%S/Inputs/CUDA_111/usr/local/cuda 2>&1 %s | \
-// RUN:    FileCheck %s --check-prefix=UNKNOWN_VERSION_H
+// Unknown version info present in cuda.h
+// RUN: %clang --target=x86_64-linux -v -### --cuda-gpu-arch=sm_60 --cuda-path=%S/Inputs/CUDA-new/usr/local/cuda 2>&1 %s | \
+// RUN:    FileCheck %s --check-prefix=NEW_VERSION
 // Make sure that we don't warn about CUDA version during C++ compilation.
 // RUN: %clang --target=x86_64-linux -v -### -x c++ --cuda-gpu-arch=sm_60 \
 // RUN:    --cuda-path=%S/Inputs/CUDA-unknown/usr/local/cuda 2>&1 %s | \
@@ -66,13 +63,15 @@
 // OK_SM35-NOT: error: GPU arch sm_35
 
 // We should only get one error per architecture.
+// ERR_SM20: error: GPU arch sm_20 {{.*}}
+// ERR_SM20-NOT: error: GPU arch sm_20
+
 // ERR_SM60: error: GPU arch sm_60 {{.*}}
 // ERR_SM60-NOT: error: GPU arch sm_60
 
 // ERR_SM61: error: GPU arch sm_61 {{.*}}
 // ERR_SM61-NOT: error: GPU arch sm_61
 
-// UNKNOWN_VERSION_V: unknown CUDA version: version.txt:{{.*}}; assuming the latest supported version
-// UNKNOWN_VERSION_H: unknown CUDA version: cuda.h: CUDA_VERSION={{.*}}; assuming the latest supported version
-// UNKNOWN_VERSION: unknown CUDA version: no version found in version.txt or cuda.h; assuming the latest supported version
+// UNKNOWN_VERSION: CUDA version [unknown] is newer than the latest{{.*}} supported version
+// NEW_VERSION: CUDA version 99010 is newer than the latest{{.*}} supported version
 // UNKNOWN_VERSION_CXX-NOT: unknown CUDA version