Index: clang/lib/Driver/ToolChains/Clang.cpp
===================================================================
--- clang/lib/Driver/ToolChains/Clang.cpp
+++ clang/lib/Driver/ToolChains/Clang.cpp
@@ -4630,8 +4630,13 @@
   TC.addClangWarningOptions(CmdArgs);
 
   // FIXME: Subclass ToolChain for SPIR and move this to addClangWarningOptions.
-  if (Triple.isSPIR() || Triple.isSPIRV())
+  if (Triple.isSPIR() || Triple.isSPIRV()) {
     CmdArgs.push_back("-Wspir-compat");
+    // SPIR-V support still needs pointer types in some cases as recovering
+    // type from pointer uses is not always possible e.g. for extern functions
+    // (see PR56660).
+    CmdArgs.push_back("-no-opaque-pointers");
+  }
 
   // Select the appropriate action.
   RewriteKind rewriteKind = RK_None;
Index: clang/test/Driver/spirv-toolchain.cl
===================================================================
--- clang/test/Driver/spirv-toolchain.cl
+++ clang/test/Driver/spirv-toolchain.cl
@@ -6,6 +6,7 @@
 // RUN: %clang -### --target=spirv64 -x c -c %s 2>&1 | FileCheck --check-prefix=SPV64 %s
 
 // SPV64: "-cc1" "-triple" "spirv64"
+// SPV64-SAME: "-no-opaque-pointers"
 // SPV64-SAME: "-o" [[BC:".*bc"]]
 // SPV64: {{llvm-spirv.*"}} [[BC]] "-o" {{".*o"}}
 
@@ -16,6 +17,7 @@
 // RUN: %clang -### --target=spirv32 -x c -c %s 2>&1 | FileCheck --check-prefix=SPV32 %s
 
 // SPV32: "-cc1" "-triple" "spirv32"
+// SPV32-SAME: "-no-opaque-pointers"
 // SPV32-SAME: "-o" [[BC:".*bc"]]
 // SPV32: {{llvm-spirv.*"}} [[BC]] "-o" {{".*o"}}