Index: lib/CodeGen/SelectionDAG/SelectionDAG.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -4049,7 +4049,8 @@
     break;
   case ISD::FNEG:
     // -(X-Y) -> (Y-X) is unsafe because when X==Y, -0.0 != +0.0
-    if (getTarget().Options.UnsafeFPMath && OpOpcode == ISD::FSUB)
+    if ((getTarget().Options.UnsafeFPMath || Flags.hasNoSignedZeros()) &&
+        OpOpcode == ISD::FSUB)
       // FIXME: FNEG has no fast-math-flags to propagate; use the FSUB's flags?
       return getNode(ISD::FSUB, DL, VT, Operand.getOperand(1),
                      Operand.getOperand(0), Operand.getNode()->getFlags());
Index: test/CodeGen/PowerPC/fmf-propagation.ll
===================================================================
--- test/CodeGen/PowerPC/fmf-propagation.ll
+++ test/CodeGen/PowerPC/fmf-propagation.ll
@@ -36,6 +36,31 @@
   ret float %add
 }
 
+; -(X - Y) --> (Y - X)
+
+; FMFDEBUG-LABEL: Optimized lowered selection DAG: %bb.0 'fneg_fsub_nozeros_1:'
+; FMFDEBUG:         fsub {{t[0-9]+}}, {{t[0-9]+}}
+; FMFDEBUG:       Type-legalized selection DAG: %bb.0 'fneg_fsub_nozeros_1:'
+
+; GLOBALDEBUG-LABEL: Optimized lowered selection DAG: %bb.0 'fneg_fsub_nozeros_1:'
+; GLOBALDEBUG:         fsub {{t[0-9]+}}, {{t[0-9]+}}
+; GLOBALDEBUG:       Type-legalized selection DAG: %bb.0 'fneg_fsub_nozeros_1:'
+
+define float @fneg_fsub_nozeros_1(float %x, float %y, float %z) {
+; FMF-LABEL: fneg_fsub_nozeros_1:
+; FMF:       # %bb.0:
+; FMF-NEXT:    xssubsp 1, 2, 1
+; FMF-NEXT:    blr
+;
+; GLOBAL-LABEL: fneg_fsub_nozeros_1:
+; GLOBAL:       # %bb.0:
+; GLOBAL-NEXT:    xssubsp 1, 2, 1
+; GLOBAL-NEXT:    blr
+  %neg = fsub float %x, %y
+  %add = fsub nsz float 0.0, %neg
+  ret float %add
+}
+
 ; This shouldn't change anything - the intermediate fmul result is now also flagged.
 
 ; FMFDEBUG-LABEL: Optimized lowered selection DAG: %bb.0 'fmul_fadd_contract2:'
@@ -166,11 +191,11 @@
 define float @fmul_fma_reassoc1(float %x) {
 ; FMF-LABEL: fmul_fma_reassoc1:
 ; FMF:       # %bb.0:
-; FMF-NEXT:    addis 3, 2, .LCPI6_0@toc@ha
-; FMF-NEXT:    addi 3, 3, .LCPI6_0@toc@l
+; FMF-NEXT:    addis 3, 2, .LCPI7_0@toc@ha
+; FMF-NEXT:    addi 3, 3, .LCPI7_0@toc@l
 ; FMF-NEXT:    lfsx 0, 0, 3
-; FMF-NEXT:    addis 3, 2, .LCPI6_1@toc@ha
-; FMF-NEXT:    addi 3, 3, .LCPI6_1@toc@l
+; FMF-NEXT:    addis 3, 2, .LCPI7_1@toc@ha
+; FMF-NEXT:    addi 3, 3, .LCPI7_1@toc@l
 ; FMF-NEXT:    lfsx 2, 0, 3
 ; FMF-NEXT:    xsmulsp 0, 1, 0
 ; FMF-NEXT:    xsmaddasp 0, 1, 2
@@ -179,8 +204,8 @@
 ;
 ; GLOBAL-LABEL: fmul_fma_reassoc1:
 ; GLOBAL:       # %bb.0:
-; GLOBAL-NEXT:    addis 3, 2, .LCPI6_0@toc@ha
-; GLOBAL-NEXT:    addi 3, 3, .LCPI6_0@toc@l
+; GLOBAL-NEXT:    addis 3, 2, .LCPI7_0@toc@ha
+; GLOBAL-NEXT:    addi 3, 3, .LCPI7_0@toc@l
 ; GLOBAL-NEXT:    lfsx 0, 0, 3
 ; GLOBAL-NEXT:    xsmulsp 1, 1, 0
 ; GLOBAL-NEXT:    blr
@@ -202,11 +227,11 @@
 define float @fmul_fma_reassoc2(float %x) {
 ; FMF-LABEL: fmul_fma_reassoc2:
 ; FMF:       # %bb.0:
-; FMF-NEXT:    addis 3, 2, .LCPI7_0@toc@ha
-; FMF-NEXT:    addi 3, 3, .LCPI7_0@toc@l
+; FMF-NEXT:    addis 3, 2, .LCPI8_0@toc@ha
+; FMF-NEXT:    addi 3, 3, .LCPI8_0@toc@l
 ; FMF-NEXT:    lfsx 0, 0, 3
-; FMF-NEXT:    addis 3, 2, .LCPI7_1@toc@ha
-; FMF-NEXT:    addi 3, 3, .LCPI7_1@toc@l
+; FMF-NEXT:    addis 3, 2, .LCPI8_1@toc@ha
+; FMF-NEXT:    addi 3, 3, .LCPI8_1@toc@l
 ; FMF-NEXT:    lfsx 2, 0, 3
 ; FMF-NEXT:    xsmulsp 0, 1, 0
 ; FMF-NEXT:    xsmaddasp 0, 1, 2
@@ -215,8 +240,8 @@
 ;
 ; GLOBAL-LABEL: fmul_fma_reassoc2:
 ; GLOBAL:       # %bb.0:
-; GLOBAL-NEXT:    addis 3, 2, .LCPI7_0@toc@ha
-; GLOBAL-NEXT:    addi 3, 3, .LCPI7_0@toc@l
+; GLOBAL-NEXT:    addis 3, 2, .LCPI8_0@toc@ha
+; GLOBAL-NEXT:    addi 3, 3, .LCPI8_0@toc@l
 ; GLOBAL-NEXT:    lfsx 0, 0, 3
 ; GLOBAL-NEXT:    xsmulsp 1, 1, 0
 ; GLOBAL-NEXT:    blr
@@ -238,11 +263,11 @@
 define float @fmul_fma_fast1(float %x) {
 ; FMF-LABEL: fmul_fma_fast1:
 ; FMF:       # %bb.0:
-; FMF-NEXT:    addis 3, 2, .LCPI8_0@toc@ha
-; FMF-NEXT:    addi 3, 3, .LCPI8_0@toc@l
+; FMF-NEXT:    addis 3, 2, .LCPI9_0@toc@ha
+; FMF-NEXT:    addi 3, 3, .LCPI9_0@toc@l
 ; FMF-NEXT:    lfsx 0, 0, 3
-; FMF-NEXT:    addis 3, 2, .LCPI8_1@toc@ha
-; FMF-NEXT:    addi 3, 3, .LCPI8_1@toc@l
+; FMF-NEXT:    addis 3, 2, .LCPI9_1@toc@ha
+; FMF-NEXT:    addi 3, 3, .LCPI9_1@toc@l
 ; FMF-NEXT:    lfsx 2, 0, 3
 ; FMF-NEXT:    xsmulsp 0, 1, 0
 ; FMF-NEXT:    xsmaddasp 0, 1, 2
@@ -251,8 +276,8 @@
 ;
 ; GLOBAL-LABEL: fmul_fma_fast1:
 ; GLOBAL:       # %bb.0:
-; GLOBAL-NEXT:    addis 3, 2, .LCPI8_0@toc@ha
-; GLOBAL-NEXT:    addi 3, 3, .LCPI8_0@toc@l
+; GLOBAL-NEXT:    addis 3, 2, .LCPI9_0@toc@ha
+; GLOBAL-NEXT:    addi 3, 3, .LCPI9_0@toc@l
 ; GLOBAL-NEXT:    lfsx 0, 0, 3
 ; GLOBAL-NEXT:    xsmulsp 1, 1, 0
 ; GLOBAL-NEXT:    blr
@@ -274,11 +299,11 @@
 define float @fmul_fma_fast2(float %x) {
 ; FMF-LABEL: fmul_fma_fast2:
 ; FMF:       # %bb.0:
-; FMF-NEXT:    addis 3, 2, .LCPI9_0@toc@ha
-; FMF-NEXT:    addi 3, 3, .LCPI9_0@toc@l
+; FMF-NEXT:    addis 3, 2, .LCPI10_0@toc@ha
+; FMF-NEXT:    addi 3, 3, .LCPI10_0@toc@l
 ; FMF-NEXT:    lfsx 0, 0, 3
-; FMF-NEXT:    addis 3, 2, .LCPI9_1@toc@ha
-; FMF-NEXT:    addi 3, 3, .LCPI9_1@toc@l
+; FMF-NEXT:    addis 3, 2, .LCPI10_1@toc@ha
+; FMF-NEXT:    addi 3, 3, .LCPI10_1@toc@l
 ; FMF-NEXT:    lfsx 2, 0, 3
 ; FMF-NEXT:    xsmulsp 0, 1, 0
 ; FMF-NEXT:    xsmaddasp 0, 1, 2
@@ -287,8 +312,8 @@
 ;
 ; GLOBAL-LABEL: fmul_fma_fast2:
 ; GLOBAL:       # %bb.0:
-; GLOBAL-NEXT:    addis 3, 2, .LCPI9_0@toc@ha
-; GLOBAL-NEXT:    addi 3, 3, .LCPI9_0@toc@l
+; GLOBAL-NEXT:    addis 3, 2, .LCPI10_0@toc@ha
+; GLOBAL-NEXT:    addi 3, 3, .LCPI10_0@toc@l
 ; GLOBAL-NEXT:    lfsx 0, 0, 3
 ; GLOBAL-NEXT:    xsmulsp 1, 1, 0
 ; GLOBAL-NEXT:    blr
@@ -317,20 +342,20 @@
 ; GLOBAL:       # %bb.0:
 ; GLOBAL-NEXT:    xxlxor 0, 0, 0
 ; GLOBAL-NEXT:    fcmpu 0, 1, 0
-; GLOBAL-NEXT:    beq 0, .LBB10_2
+; GLOBAL-NEXT:    beq 0, .LBB11_2
 ; GLOBAL-NEXT:  # %bb.1:
 ; GLOBAL-NEXT:    xsrsqrtesp 2, 1
-; GLOBAL-NEXT:    addis 3, 2, .LCPI10_0@toc@ha
+; GLOBAL-NEXT:    addis 3, 2, .LCPI11_0@toc@ha
 ; GLOBAL-NEXT:    fneg 0, 1
 ; GLOBAL-NEXT:    fmr 4, 1
-; GLOBAL-NEXT:    addi 3, 3, .LCPI10_0@toc@l
+; GLOBAL-NEXT:    addi 3, 3, .LCPI11_0@toc@l
 ; GLOBAL-NEXT:    lfsx 3, 0, 3
 ; GLOBAL-NEXT:    xsmaddasp 4, 0, 3
 ; GLOBAL-NEXT:    xsmulsp 0, 2, 2
 ; GLOBAL-NEXT:    xsmaddasp 3, 4, 0
 ; GLOBAL-NEXT:    xsmulsp 0, 2, 3
 ; GLOBAL-NEXT:    xsmulsp 0, 0, 1
-; GLOBAL-NEXT:  .LBB10_2:
+; GLOBAL-NEXT:  .LBB11_2:
 ; GLOBAL-NEXT:    fmr 1, 0
 ; GLOBAL-NEXT:    blr
   %rt = call afn float @llvm.sqrt.f32(float %x)
@@ -351,26 +376,26 @@
 ; FMF-LABEL: sqrt_fast:
 ; FMF:       # %bb.0:
 ; FMF-NEXT:    xssqrtsp 1, 1
-; FMF-NEXT:    blr
+; FMF:         blr
 ;
 ; GLOBAL-LABEL: sqrt_fast:
 ; GLOBAL:       # %bb.0:
 ; GLOBAL-NEXT:    xxlxor 0, 0, 0
 ; GLOBAL-NEXT:    fcmpu 0, 1, 0
-; GLOBAL-NEXT:    beq 0, .LBB11_2
+; GLOBAL-NEXT:    beq 0, .LBB12_2
 ; GLOBAL-NEXT:  # %bb.1:
 ; GLOBAL-NEXT:    xsrsqrtesp 2, 1
-; GLOBAL-NEXT:    addis 3, 2, .LCPI11_0@toc@ha
+; GLOBAL-NEXT:    addis 3, 2, .LCPI12_0@toc@ha
 ; GLOBAL-NEXT:    fneg 0, 1
 ; GLOBAL-NEXT:    fmr 4, 1
-; GLOBAL-NEXT:    addi 3, 3, .LCPI11_0@toc@l
+; GLOBAL-NEXT:    addi 3, 3, .LCPI12_0@toc@l
 ; GLOBAL-NEXT:    lfsx 3, 0, 3
 ; GLOBAL-NEXT:    xsmaddasp 4, 0, 3
 ; GLOBAL-NEXT:    xsmulsp 0, 2, 2
 ; GLOBAL-NEXT:    xsmaddasp 3, 4, 0
 ; GLOBAL-NEXT:    xsmulsp 0, 2, 3
 ; GLOBAL-NEXT:    xsmulsp 0, 0, 1
-; GLOBAL-NEXT:  .LBB11_2:
+; GLOBAL-NEXT:  .LBB12_2:
 ; GLOBAL-NEXT:    fmr 1, 0
 ; GLOBAL-NEXT:    blr
   %rt = call fast float @llvm.sqrt.f32(float %x)
@@ -392,10 +417,10 @@
 ; FMF:       # %bb.0:
 ; FMF-NEXT:    xxlxor 0, 0, 0
 ; FMF-NEXT:    xscmpudp 0, 1, 0
-; FMF-NEXT:    blt 0, .LBB12_2
+; FMF-NEXT:    blt 0, .LBB13_2
 ; FMF-NEXT:  # %bb.1:
 ; FMF-NEXT:    fmr 3, 2
-; FMF-NEXT:  .LBB12_2:
+; FMF-NEXT:  .LBB13_2:
 ; FMF-NEXT:    fmr 1, 3
 ; FMF-NEXT:    blr
 ;
@@ -403,10 +428,10 @@
 ; GLOBAL:       # %bb.0:
 ; GLOBAL-NEXT:    xxlxor 0, 0, 0
 ; GLOBAL-NEXT:    xscmpudp 0, 1, 0
-; GLOBAL-NEXT:    blt 0, .LBB12_2
+; GLOBAL-NEXT:    blt 0, .LBB13_2
 ; GLOBAL-NEXT:  # %bb.1:
 ; GLOBAL-NEXT:    fmr 3, 2
-; GLOBAL-NEXT:  .LBB12_2:
+; GLOBAL-NEXT:  .LBB13_2:
 ; GLOBAL-NEXT:    fmr 1, 3
 ; GLOBAL-NEXT:    blr
   %cmp = fcmp nnan ult double %a, 0.0