diff --git a/gcc/common.opt b/gcc/common.opt
index 8a0dafc522d12..73b69ba3118e4 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -1786,6 +1786,10 @@ fif-conversion2
 Common Var(flag_if_conversion2) Optimization
 Perform conversion of conditional jumps to conditional execution.
 
+multiflags
+Common Driver
+Building block for specs-based multilib-aware TFLAGS.
+
 fstack-reuse=
 Common Joined RejectNegative Enum(stack_reuse_level) Var(flag_stack_reuse) Init(SR_ALL) Optimization
 -fstack-reuse=[all|named_vars|none]	Set stack reuse level for local variables.
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 98a543ae06fda..0bd8d7b129612 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -727,7 +727,7 @@ Objective-C and Objective-C++ Dialects}.
 -fsel-sched-verbose  -fsel-sched-dump-cfg  -fsel-sched-pipelining-verbose @gol
 -fstats  -fstack-usage  -ftime-report  -ftime-report-details @gol
 -fvar-tracking-assignments-toggle  -gtoggle @gol
--print-file-name=@var{library}  -print-libgcc-file-name @gol
+-multiflags  -print-file-name=@var{library}  -print-libgcc-file-name @gol
 -print-multi-directory  -print-multi-lib  -print-multi-os-directory @gol
 -print-prog-name=@var{program}  -print-search-dirs  -Q @gol
 -print-sysroot  -print-sysroot-headers-suffix @gol
@@ -18870,6 +18870,34 @@ For example, with @option{-fdbg-cnt=dce:2-4:10-11,tail_call:10},
 eleventh invocation.
 For @code{dbg_cnt(tail_call)} true is returned for first 10 invocations.
 
+@item -multiflags
+@opindex multiflags
+This option enables multilib-aware @code{TFLAGS} to be used to build
+target libraries with options different from those the compiler is
+configured to use by default, through the use of specs (@xref{Spec
+Files}) set up by compiler internals, by the target, or by builders at
+configure time.
+
+Like @code{TFLAGS}, this allows the target libraries to be built for
+portable baseline environments, while the compiler defaults to more
+demanding ones.  That's useful because users can easily override the
+defaults the compiler is configured to use to build their own programs,
+if the defaults are not ideal for their target environment, whereas
+rebuilding the runtime libraries is usually not as easy or desirable.
+
+Unlike @code{TFLAGS}, the use of specs enables different flags to be
+selected for different multilibs.  The way to accomplish that is to
+build with @samp{make TFLAGS=-multiflags}, after configuring
+@samp{--with-specs=%@{multiflags:...@}}.
+
+This option is discarded by the driver once it's done processing driver
+self spec.
+
+It is also useful to check that @code{TFLAGS} are being used to build
+all target libraries, by configuring a non-bootstrap compiler
+@samp{--with-specs='%@{!multiflags:%emissing TFLAGS@}'} and building the
+compiler and target libraries.
+
 @item -print-file-name=@var{library}
 @opindex print-file-name
 Print the full absolute name of the library file @var{library} that
diff --git a/gcc/gcc.cc b/gcc/gcc.cc
index 299e09c4f545f..fd9523c48f1e9 100644
--- a/gcc/gcc.cc
+++ b/gcc/gcc.cc
@@ -1347,7 +1347,11 @@ static const char *const multilib_defaults_raw[] = MULTILIB_DEFAULTS;
 
 static const char *const driver_self_specs[] = {
   "%{fdump-final-insns:-fdump-final-insns=.} %<fdump-final-insns",
-  DRIVER_SELF_SPECS, CONFIGURE_SPECS, GOMP_SELF_SPECS, GTM_SELF_SPECS
+  DRIVER_SELF_SPECS, CONFIGURE_SPECS, GOMP_SELF_SPECS, GTM_SELF_SPECS,
+  /* This discards -multiflags at the end of self specs processing in the
+     driver, so that it is effectively Ignored, without actually marking it as
+     Ignored, which would get it discarded before self specs could remap it.  */
+  "%<multiflags"
 };
 
 #ifndef OPTION_DEFAULT_SPECS
diff --git a/gcc/opts.cc b/gcc/opts.cc
index f0c5c4db95571..f0cf6ded55f0a 100644
--- a/gcc/opts.cc
+++ b/gcc/opts.cc
@@ -3203,6 +3203,10 @@ common_handle_option (struct gcc_options *opts,
       dc->report_bug = value;
       break;
 
+    case OPT_multiflags:
+      gcc_checking_assert (lang_mask == CL_DRIVER);
+      break;
+
     default:
       /* If the flag was handled in a standard way, assume the lack of
 	 processing here is intentional.  */
