--- msvc.jam	(revision 50869)
+++ msvc.jam	(patch msvc_asm level 1)

@@ -296,14 +296,13 @@

 
 # For the assembler the following options are turned on by default:
 #
-#   -coff  generate COFF format object file (compatible with cl.exe output)
 #   -Zp4   align structures to 4 bytes
 #   -Cp    preserve case of user identifiers
 #   -Cx    preserve case in publics, externs
 #
 actions compile.asm
 {
-    $(.ASM) -nologo -c -coff -Zp4 -Cp -Cx $(USER_ASMFLAGS) -Fo "$(<:W)" "$(>:W)"
+    $(.ASM) -c -Zp4 -Cp -Cx -D$(DEFINES) $(ASMFLAGS) $(USER_ASMFLAGS) -Fo "$(<:W)" "$(>:W)"
 }
 
 
@@ -852,8 +851,11 @@

         resource-compiler = [ feature.get-values <resource-compiler> : $(options) ] ;
         resource-compiler ?= rc ;
 
+        local default-assembler-amd64 = ml64 ;
+        local default-assembler-i386  = "ml -coff" ;
+        local default-assembler-ia64  = ias ;
+
         assembler = [ feature.get-values <assembler> : $(options) ] ;
-        assembler ?= ml ;
 
         idl-compiler = [ feature.get-values <idl-compiler> : $(options) ] ;
         idl-compiler ?= midl ;
@@ -880,9 +882,12 @@

                 }
             }
 
+            local cpu-assembler = $(assembler) ;
+            cpu-assembler ?= $(default-assembler-$(c)) ;
+
             toolset.flags msvc.compile .CC  $(cpu-conditions) : $(setup-$(c))$(compiler) /Zm800 -nologo ;
             toolset.flags msvc.compile .RC  $(cpu-conditions) : $(setup-$(c))$(resource-compiler) ;
-            toolset.flags msvc.compile .ASM $(cpu-conditions) : $(setup-$(c))$(assembler) ;
+            toolset.flags msvc.compile .ASM $(cpu-conditions) : $(setup-$(c))$(cpu-assembler) -nologo ;
             toolset.flags msvc.link    .LD  $(cpu-conditions) : $(setup-$(c))$(linker) /NOLOGO /INCREMENTAL:NO ;
             toolset.flags msvc.archive .LD  $(cpu-conditions) : $(setup-$(c))$(linker) /lib /NOLOGO  ;
             toolset.flags msvc.compile .IDL $(cpu-conditions) : $(setup-$(c))$(idl-compiler) ;
@@ -1113,6 +1118,15 @@

     # Declare flags for the assembler.
     toolset.flags msvc.compile.asm USER_ASMFLAGS <asmflags> ;
 
+    toolset.flags msvc.compile.asm ASMFLAGS <debug-symbols>on : "/Zi /Zd" ;
+
+    toolset.flags msvc.compile.asm ASMFLAGS <warnings>on : /W3 ;
+    toolset.flags msvc.compile.asm ASMFLAGS <warnings>off : /W0 ;
+    toolset.flags msvc.compile.asm ASMFLAGS <warnings>all : /W4 ;
+    toolset.flags msvc.compile.asm ASMFLAGS <warnings-as-errors>on : /WX ;
+
+    toolset.flags msvc.compile.asm DEFINES <define> ;
+
     # Declare flags for linking.
     {
         toolset.flags msvc.link PDB_LINKFLAG <debug-symbols>on/<debug-store>database : /PDB: ;  # not used yet