diff --git a/Changes b/Changes
index a6df83cea..d7ab9fbd1 100644
--- a/Changes
+++ b/Changes
@@ -481,6 +481,10 @@ Working version
   (Xavier Leroy, report by Alain Frisch, review by Nicolás Ojeda Bär
   and Alain Frisch)
 
+- #9925: Correct passing -fdebug-prefix-map to flexlink on Cygwin by prefixing
+  it with -link.
+  (David Allsopp, review by ???)
+
 
 OCaml 4.11.1
 ------------
diff --git a/bytecomp/bytelink.ml b/bytecomp/bytelink.ml
index b8c874b23..6660fee46 100644
--- a/bytecomp/bytelink.ml
+++ b/bytecomp/bytelink.ml
@@ -573,7 +573,13 @@ let build_custom_runtime prim_name exec_name =
     else "-lcamlrun" ^ !Clflags.runtime_variant in
   let debug_prefix_map =
     if Config.c_has_debug_prefix_map && not !Clflags.keep_camlprimc_file then
-      [Printf.sprintf "-fdebug-prefix-map=%s=camlprim.c" prim_name]
+      let flag =
+        [Printf.sprintf "-fdebug-prefix-map=%s=camlprim.c" prim_name]
+      in
+        if Ccomp.linker_is_flexlink then
+          "-link" :: flag
+        else
+          flag
     else
       [] in
   let exitcode =
diff --git a/utils/ccomp.ml b/utils/ccomp.ml
index 429273a03..22b60a8b9 100644
--- a/utils/ccomp.ml
+++ b/utils/ccomp.ml
@@ -206,3 +206,9 @@ let call_linker mode output_name files extra =
     in
     command cmd
   )
+
+let linker_is_flexlink =
+  (* Config.mkexe, Config.mkdll and Config.mkmaindll are all flexlink
+     invocations for the native Windows ports and for Cygwin, if shared library
+     support is enabled. *)
+  Sys.win32 || Config.supports_shared_libraries && Sys.cygwin
diff --git a/utils/ccomp.mli b/utils/ccomp.mli
index 89724252b..fb520e2a4 100644
--- a/utils/ccomp.mli
+++ b/utils/ccomp.mli
@@ -37,3 +37,5 @@ type link_mode =
   | Partial
 
 val call_linker: link_mode -> string -> string list -> string -> int
+
+val linker_is_flexlink : bool