On newsmips (big-endian mips), it seems to work with the following patch.
libgcc, libobjc, and libg2c are compiled successfully.

*** dist/gcc/config/mips/netbsd.h.orig	Mon Aug 17 13:56:56 1998
--- dist/gcc/config/mips/netbsd.h	Thu Aug 20 01:12:28 1998
***************
*** 20,32 ****
--- 20,38 ----
  
  /* Define default target values. */
  
+ #ifdef __MIPSEL__
  #define TARGET_ENDIAN_DEFAULT 0
+ #else
+ #define TARGET_ENDIAN_DEFAULT MASK_BIG_ENDIAN
+ #endif
  #define TARGET_DEFAULT MASK_GAS
  
  /* Get generic mips ELF definitions. */
  
  #include <mips/elf.h>
  
+ #undef OBJECT_FORMAT_COFF
+ 
  /* Get generic NetBSD definitions. */
  
  #define NETBSD_ELF
***************
*** 34,44 ****
--- 40,67 ----
  
  /* Define mips-specific netbsd predefines... */
  
+ #if 1	/* needed? */
+ #undef LOCAL_LABEL_PREFIX
+ #define LOCAL_LABEL_PREFIX "."
+ #endif
+ 
+ #undef MIPS_DEFAULT_GVALUE
+ #define MIPS_DEFAULT_GVALUE 0
+ 
+ #define DWARF2_UNWIND_INFO 0
+ 
  #undef CPP_PREDEFINES
+ #ifdef __MIPSEL__
  #define CPP_PREDEFINES \
   "-D__ANSI_COMPAT -DMIPSEL -DR3000 -DSYSTYPE_BSD -D_SYSTYPE_BSD \
    -D__NetBSD__ -D__ELF__ -Dmips -D__NO_LEADING_UNDERSCORES__ -D__GP_SUPPORT__ \
    -Dunix -D_R3000 -Asystem(unix) -Asystem(NetBSD) -Amachine(mips)"
+ #else
+ #define CPP_PREDEFINES \
+  "-D__ANSI_COMPAT -DMIPSEB -DR3000 -DSYSTYPE_BSD -D_SYSTYPE_BSD \
+   -D__NetBSD__ -D__ELF__ -Dmips -D__NO_LEADING_UNDERSCORES__ -D__GP_SUPPORT__ \
+   -Dunix -D_R3000 -Asystem(unix) -Asystem(NetBSD) -Amachine(mips)"
+ #endif
  
  /* Always uses gas.  */
  
***************
*** 242,244 ****
--- 265,276 ----
  
  /* Since gas and gld are standard on NetBSD, we don't need these */
  #undef ASM_FINAL_SPEC
+ 
+ #define ASM_OUTPUT_DEFINE_LABEL_DIFFERENCE_SYMBOL(FILE, SY, HI, LO)    	\
+  do {									\
+   assemble_name (FILE, SY);						\
+   fputc ('=', FILE);							\
+   assemble_name (FILE, HI);						\
+   fputc ('-', FILE);							\
+   assemble_name (FILE, LO);						\
+  } while (0)