Index: /trunk/src/VBox/Frontends/VirtualBox/Makefile.kmk
===================================================================
--- /trunk/src/VBox/Frontends/VirtualBox/Makefile.kmk	(revision 75441)
+++ /trunk/src/VBox/Frontends/VirtualBox/Makefile.kmk	(revision 75442)
@@ -2239,12 +2239,20 @@
 
 #
-# Precompiled header - non-functional atm.
+# Precompiled header
+# 	win.amd64 without:  kmk_time: 3m51.962058s
+# 	win.amd64 with:     kmk_time: 2m23.336252s
 #
 ifdef VBOX_WITH_PRECOMPILED_HEADERS
  if1of ($(KBUILD_TARGET),win)
-  VirtualBox_USES    += vccprecomp
-  VirtualBox_PCH_HDR := $(PATH_SUB_CURRENT)/src/precomp_vcc.h
-
- else # obsolete experiment
+  VirtualBox_USES      += vccprecomp
+  VirtualBox_PCH_HDR   := $(PATH_SUB_CURRENT)/src/precomp_vcc.h
+
+  VirtualBoxVM_USES    += vccprecomp
+  VirtualBoxVM_PCH_HDR := $(PATH_SUB_CURRENT)/src/precomp_vcc.h
+
+  VBoxGlobal_USES      += vccprecomp
+  VBoxGlobal_PCH_HDR   := $(PATH_SUB_CURRENT)/src/precomp_vcc.h
+
+ else if 0 # Obsolete experiment - non-functional.  Needs to be redone the same way as on windows.
   VirtualBox_DEFS           += VBOX_WITH_PRECOMPILED_HEADERS
   VirtualBox_INCS           <= $(VirtualBoxPch_0_OUTDIR)/src